Code — Elixir v1.16.3

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# View Source Code (Elixir v1.16.3)

Utilities for managing code compilation, code evaluation, and code loading.

This module complements Erlang's `:code` module to add behaviour which is specific to Elixir. For functions to manipulate Elixir's AST (rather than evaluating it), see the `Macro` module.

## Working with files

This module contains three functions for compiling and evaluating files. Here is a summary of them and their behaviour:

- `require_file/2` - compiles a file and tracks its name. It does not compile the file again if it has been previously required.

- `compile_file/2` - compiles a file without tracking its name. Compiles the file multiple times when invoked multiple times.

- `eval_file/2` - evaluates the file contents without tracking its name. It returns the result of the last expression in the file, instead of the modules defined in it. Evaluated files do not trigger the compilation tracers described in the next section.

In a nutshell, the first must be used when you want to keep track of the files handled by the system, to avoid the same file from being compiled multiple times. This is common in scripts.

`compile_file/2` must be used when you are interested in the modules defined in a file, without tracking. `eval_file/2` should be used when you are interested in the result of evaluating the file rather than the modules it defines.

The functions above work with Elixir source. If you want to work with modules compiled to bytecode, which have the `.beam` extension and are typically found below the _build directory of a Mix project, see the functions in Erlang's `:code` module.

## Code loading on the Erlang VM

Erlang has two modes to load code: interactive and embedded.

By default, the Erlang VM runs in interactive mode, where modules are loaded as needed. In embedded mode the opposite happens, as all modules need to be loaded upfront or explicitly.

You can use `ensure_loaded/1` (as well as `ensure_loaded?/1` and `ensure_loaded!/1`) to check if a module is loaded before using it and act.

## `ensure_compiled/1` and `ensure_compiled!/1`

Elixir also includes `ensure_compiled/1` and `ensure_compiled!/1` functions that are a superset of `ensure_loaded/1`.

Since Elixir's compilation happens in parallel, in some situations you may need to use a module that was not yet compiled, therefore it can't even be loaded.

When invoked, `ensure_compiled/1` and `ensure_compiled!/1` halt the compilation of the caller until the module becomes available. Note that the distinction between `ensure_compiled/1` and `ensure_compiled!/1` is important: if you are using `ensure_compiled!/1`, you are indicating to the compiler that you can only continue if said module is available.

If you are using `Code.ensure_compiled/1`, you are implying you may continue without the module and therefore Elixir may return `{:error, :unavailable}` for cases where the module is not yet available (but may be available later on).

For those reasons, developers must typically use `Code.ensure_compiled!/1`. In particular, do not do this:

    case Code.ensure_compiled(module) do
      {:module, _} -> module
      {:error, _} -> raise ...
    end

Finally, note you only need `ensure_compiled!/1` to check for modules being defined within the same project. It does not apply to modules from dependencies as dependencies are always compiled upfront.

In most cases, `ensure_loaded/1` is enough. `ensure_compiled!/1` must be used in rare cases, usually involving macros that need to invoke a module for callback information. The use of `ensure_compiled/1` is even less likely.

## Compilation tracers

Elixir supports compilation tracers, which allow modules to observe constructs handled by the Elixir compiler when compiling files. A tracer is a module that implements the `trace/2` function. The function receives the event name as first argument and `Macro.Env` as second and it must return `:ok`. It is very important for a tracer to do as little work as possible synchronously and dispatch the bulk of the work to a separate process. Slow tracers will slow down compilation.

You can configure your list of tracers via `put_compiler_option/2`. The following events are available to tracers:

- `:start` - (since v1.11.0) invoked whenever the compiler starts to trace a new lexical context. A lexical context is started when compiling a new file or when defining a module within a function. Note evaluated code does not start a new lexical context (because they don't track unused aliases, imports, etc) but defining a module inside evaluated code will.

  Note this event may be emitted in parallel, where multiple files/modules invoke `:start` and run at the same time. The value of the `lexical_tracker` of the macro environment, albeit opaque, can be used to uniquely identify the environment.

- `:stop` - (since v1.11.0) invoked whenever the compiler stops tracing a new lexical context, such as a new file.

- `{:import, meta, module, opts}` - traced whenever `module` is imported. `meta` is the import AST metadata and `opts` are the import options.

- `{:imported_function, meta, module, name, arity}` and `{:imported_macro, meta, module, name, arity}` - traced whenever an imported function or macro is invoked. `meta` is the call AST metadata, `module` is the module the import is from, followed by the `name` and `arity` of the imported function/macro. A :remote_function/:remote_macro event may still be emitted for the imported module/name/arity.

- `{:alias, meta, alias, as, opts}` - traced whenever `alias` is aliased to `as`. `meta` is the alias AST metadata and `opts` are the alias options.

- `{:alias_expansion, meta, as, alias}` traced whenever there is an alias expansion for a previously defined `alias`, i.e. when the user writes `as` which is expanded to `alias`. `meta` is the alias expansion AST metadata.

- `{:alias_reference, meta, module}` - traced whenever there is an alias in the code, i.e. whenever the user writes `MyModule.Foo.Bar` in the code, regardless if it was expanded or not.

- `{:require, meta, module, opts}` - traced whenever `module` is required. `meta` is the require AST metadata and `opts` are the require options. If the `meta` option contains the `:from_macro`, then module was called from within a macro and therefore must be treated as a compile-time dependency.

- `{:struct_expansion, meta, module, keys}` - traced whenever `module`'s struct is expanded. `meta` is the struct AST metadata and `keys` are the keys being used by expansion

- `{:remote_function, meta, module, name, arity}` and `{:remote_macro, meta, module, name, arity}` - traced whenever a remote function or macro is referenced. `meta` is the call AST metadata, `module` is the invoked module, followed by the `name` and `arity`.

- `{:local_function, meta, name, arity}` and `{:local_macro, meta, name, arity}` - traced whenever a local function or macro is referenced. `meta` is the call AST metadata, followed by the `name` and `arity`.

- `{:compile_env, app, path, return}` - traced whenever `Application.compile_env/3` or `Application.compile_env!/2` are called. `app` is an atom, `path` is a list of keys to traverse in the application environment and `return` is either `{:ok, value}` or `:error`.

- `:defmodule` - (since v1.16.2) traced as soon as the definition of a module starts. This is invoked early on in the module life-cycle, `Module.open?/1` still returns `false` for such traces

- `{:on_module, bytecode, _ignore}` - (since v1.13.0) traced whenever a module is defined. This is equivalent to the `@after_compile` callback and invoked after any `@after_compile` in the given module. The third element is currently `:none` but it may provide more metadata in the future. It is best to ignore it at the moment. Note that `Module` functions expecting not yet compiled modules (such as `Module.definitions_in/1`) are still available at the time this event is emitted.

The `:tracers` compiler option can be combined with the `:parser_options` compiler option to enrich the metadata of the traced events above.

New events may be added at any time in the future, therefore it is advised for the `trace/2` function to have a "catch-all" clause.

Below is an example tracer that prints all remote function invocations:

    defmodule MyTracer do
      def trace({:remote_function, _meta, module, name, arity}, env) do
        IO.puts "#{env.file}:#{env.line} #{inspect(module)}.#{name}/#{arity}"
        :ok
      end

      def trace(_event, _env) do
        :ok
      end
    end

# Summary

## Types

binding()

A list with all variables and their values.

diagnostic(severity)

Diagnostics returned by the compiler and code evaluation.

line()

The line. 0 indicates no line.

position()

The position of the diagnostic.

## Functions

append_path(path, opts \\ [])

Appends a path to the Erlang VM code path list.

append_paths(paths, opts \\ [])

Appends a list of `paths` to the Erlang VM code path list.

available_compiler_options()

Returns a list with all available compiler options.

can_await_module_compilation?()

Returns `true` if the current process can await for module compilation.

compile_file(file, relative_to \\ nil)

Compiles the given file.

compile_quoted(quoted, file \\ "nofile")

Compiles the quoted expression.

compile_string(string, file \\ "nofile")

Compiles the given string.

compiler_options()

Gets all compilation options from the code server.

compiler_options(opts)

Stores all given compilation options.

delete_path(path)

Deletes a path from the Erlang VM code path list.

delete_paths(paths)

Deletes a list of paths from the Erlang VM code path list.

ensure_all_loaded(modules)

Ensures the given modules are loaded.

ensure_all_loaded!(modules)

Same as `ensure_all_loaded/1` but raises if any of the modules cannot be loaded.

ensure_compiled(module)

Similar to `ensure_compiled!/1` but indicates you can continue without said module.

ensure_compiled!(module)

Ensures the given module is compiled and loaded.

ensure_loaded(module)

Ensures the given module is loaded.

ensure_loaded!(module)

Same as `ensure_loaded/1` but raises if the module cannot be loaded.

ensure_loaded?(module)

Ensures the given module is loaded.

env_for_eval(env_or_opts)

Returns an environment for evaluation.

eval_file(file, relative_to \\ nil)

Evaluates the given file.

eval_quoted(quoted, binding \\ [], env_or_opts \\ [])

Evaluates the quoted contents.

eval_quoted_with_env(quoted, binding, env, opts \\ [])

Evaluates the given `quoted` contents with `binding` and `env`.

eval_string(string, binding \\ [], opts \\ [])

Evaluates the contents given by `string`.

fetch_docs(module_or_path)

Returns the docs for the given module or path to `.beam` file.

format_file!(file, opts \\ [])

Formats a file.

format_string!(string, opts \\ [])

Formats the given code `string`.

get_compiler_option(key)

Returns the value of a given compiler option.

loaded?(module)

Returns `true` if the module is loaded.

prepend_path(path, opts \\ [])

Prepends a path to the Erlang VM code path list.

prepend_paths(paths, opts \\ [])

Prepends a list of `paths` to the Erlang VM code path list.

print_diagnostic(diagnostic, opts \\ [])

Prints a diagnostic into the standard error.

purge_compiler_modules()

Purge compiler modules.

put_compiler_option(key, value)

Stores a compilation option.

quoted_to_algebra(quoted, opts \\ [])

Converts a quoted expression to an algebra document using Elixir's formatter rules.

require_file(file, relative_to \\ nil)

Requires the given `file`.

required_files()

Lists all required files.

string_to_quoted(string, opts \\ [])

Converts the given string to its quoted form.

string_to_quoted!(string, opts \\ [])

Converts the given string to its quoted form.

string_to_quoted_with_comments(string, opts \\ [])

Converts the given string to its quoted form and a list of comments.

string_to_quoted_with_comments!(string, opts \\ [])

Converts the given string to its quoted form and a list of comments.

unrequire_files(files)

Removes files from the required files list.

with_diagnostics(opts \\ [], fun)

Executes the given `fun` and capture all diagnostics.

# Types

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# binding()

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    @type binding() :: [{atom() | tuple(), any()}]

A list with all variables and their values.

The binding keys are usually atoms, but they may be a tuple for variables defined in a different context.

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# diagnostic(severity)

View Source

    @type diagnostic(severity) :: %{
      :source => Path.t() | nil,
      :file => Path.t() | nil,
      :severity => severity,
      :message => String.t(),
      :position => position(),
      :stacktrace => Exception.stacktrace(),
      :span => {line :: pos_integer(), column :: pos_integer()} | nil,
      optional(:details) => term(),
      optional(any()) => any()
    }

Diagnostics returned by the compiler and code evaluation.

The file and position relate to where the diagnostic should be shown. If there is a file and position, then the diagnostic is precise and you can use the given file and position for generating snippets, IDEs annotations, and so on. An optional span is available with the line and column the diagnostic ends.

Otherwise, a stacktrace may be given, which you can place your own heuristics to provide better reporting.

The source field points to the source file the compiler tracked the error to. For example, a file `lib/foo.ex` may embed `.eex` templates from `lib/foo/bar.eex`. A syntax error on the EEx template will point to file `lib/foo/bar.eex` but the source is `lib/foo.ex`.

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# line()

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    @type line() :: non_neg_integer()

The line. 0 indicates no line.

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# position()

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    @type position() :: line() | {line :: pos_integer(), column :: pos_integer()}

The position of the diagnostic.

Can be either a line number or a `{line, column}`. Line and columns numbers are one-based. A position of `0` represents unknown.

# Functions

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# append_path(path, opts \\ [])

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    @spec append_path(Path.t(), [{:cache, boolean()}]) :: true | false

Appends a path to the Erlang VM code path list.

This is the list of directories the Erlang VM uses for finding module code. The list of files is managed per Erlang VM node.

The path is expanded with `Path.expand/1` before being appended. It requires the path to exist. Returns a boolean indicating if the path was successfully added.

## Examples

    Code.append_path(".")
    #=> true

    Code.append_path("/does_not_exist")
    #=> false

## Options

- `:cache` - (since v1.15.0) when true, the code path is cached the first time it is traversed in order to reduce file system operations. It requires Erlang/OTP 26, otherwise it is a no-op.

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# append_paths(paths, opts \\ [])

View Source (since 1.15.0)

    @spec append_paths([Path.t()], [{:cache, boolean()}]) :: :ok

Appends a list of `paths` to the Erlang VM code path list.

This is the list of directories the Erlang VM uses for finding module code. The list of files is managed per Erlang VM node.

All paths are expanded with `Path.expand/1` before being appended. Only existing paths are appended. This function always returns `:ok`, regardless of how many paths were appended. Use `append_path/1` if you need more control.

## Examples

    Code.append_paths([".", "/does_not_exist"])
    #=> :ok

## Options

- `:cache` - when true, the code path is cached the first time it is traversed in order to reduce file system operations. It requires Erlang/OTP 26, otherwise it is a no-op.

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# available_compiler_options()

View Source

    @spec available_compiler_options() :: [atom()]

Returns a list with all available compiler options.

For a description of all options, see `put_compiler_option/2`.

## Examples

    Code.available_compiler_options()
    #=> [:docs, :debug_info, ...]

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# can_await_module_compilation?()

View Source (since 1.11.0)

    @spec can_await_module_compilation?() :: boolean()

Returns `true` if the current process can await for module compilation.

When compiling Elixir code via `Kernel.ParallelCompiler`, which is used by Mix and `elixirc`, calling a module that has not yet been compiled will block the caller until the module becomes available. Executing Elixir scripts, such as passing a filename to `elixir`, does not await.

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# compile_file(file, relative_to \\ nil)

View Source (since 1.7.0)

    @spec compile_file(binary(), nil | binary()) :: [{module(), binary()}]

Compiles the given file.

Accepts `relative_to` as an argument to tell where the file is located.

Returns a list of tuples where the first element is the module name and the second one is its bytecode (as a binary). Opposite to `require_file/2`, it does not track the filename of the compiled file.

If you would like to get the result of evaluating file rather than the modules defined in it, see `eval_file/2`.

For compiling many files concurrently, see `Kernel.ParallelCompiler.compile/2`.

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# compile_quoted(quoted, file \\ "nofile")

View Source

    @spec compile_quoted(Macro.t(), binary()) :: [{module(), binary()}]

Compiles the quoted expression.

Returns a list of tuples where the first element is the module name and the second one is its bytecode (as a binary). A `file` can be given as second argument which will be used for reporting warnings and errors.

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# compile_string(string, file \\ "nofile")

View Source

    @spec compile_string(List.Chars.t(), binary()) :: [{module(), binary()}]

Compiles the given string.

Returns a list of tuples where the first element is the module name and the second one is its bytecode (as a binary). A `file` can be given as second argument which will be used for reporting warnings and errors.

Warning: `string` can be any Elixir code and code can be executed with the same privileges as the Erlang VM: this means that such code could compromise the machine (for example by executing system commands). Don't use `compile_string/2` with untrusted input (such as strings coming from the network).

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# compiler_options()

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    @spec compiler_options() :: map()

Gets all compilation options from the code server.

To get individual options, see `get_compiler_option/1`. For a description of all options, see `put_compiler_option/2`.

## Examples

    Code.compiler_options()
    #=> %{debug_info: true, docs: true, ...}

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# compiler_options(opts)

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    @spec compiler_options(Enumerable.t({atom(), term()})) :: %{
      optional(atom()) => term()
    }

Stores all given compilation options.

Changing the compilation options affect all processes running in a given Erlang VM node. To store individual options and for a description of all options, see `put_compiler_option/2`.

Returns a map with previous values.

## Examples

    Code.compiler_options(warnings_as_errors: true)
    #=> %{warnings_as_errors: false}

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# delete_path(path)

View Source

    @spec delete_path(Path.t()) :: boolean()

Deletes a path from the Erlang VM code path list.

This is the list of directories the Erlang VM uses for finding module code. The list of files is managed per Erlang VM node.

The path is expanded with `Path.expand/1` before being deleted. If the path does not exist, this function returns `false`.

## Examples

    Code.prepend_path(".")
    Code.delete_path(".")
    #=> true

    Code.delete_path("/does_not_exist")
    #=> false

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# delete_paths(paths)

View Source (since 1.15.0)

    @spec delete_paths([Path.t()]) :: :ok

Deletes a list of paths from the Erlang VM code path list.

This is the list of directories the Erlang VM uses for finding module code. The list of files is managed per Erlang VM node.

The path is expanded with `Path.expand/1` before being deleted. If the path does not exist, this function returns `false`.

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# ensure_all_loaded(modules)

View Source (since 1.15.0)

    @spec ensure_all_loaded([module()]) :: :ok | {:error, [{module(), reason}]}
    when reason: :badfile | :nofile | :on_load_failure

Ensures the given modules are loaded.

Similar to `ensure_loaded/1`, but accepts a list of modules instead of a single module, and loads all of them.

If all modules load successfully, returns `:ok`. Otherwise, returns `{:error, errors}` where `errors` is a list of tuples made of the module and the reason it failed to load.

## Examples

    iex> Code.ensure_all_loaded([Atom, String])
    :ok

    iex> Code.ensure_all_loaded([Atom, DoesNotExist])
    {:error, [{DoesNotExist, :nofile}]}

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# ensure_all_loaded!(modules)

View Source (since 1.15.0)

    @spec ensure_all_loaded!([module()]) :: :ok

Same as `ensure_all_loaded/1` but raises if any of the modules cannot be loaded.

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# ensure_compiled(module)

View Source

    @spec ensure_compiled(module()) ::
      {:module, module()}
      | {:error, :embedded | :badfile | :nofile | :on_load_failure | :unavailable}

Similar to `ensure_compiled!/1` but indicates you can continue without said module.

While `ensure_compiled!/1` indicates to the Elixir compiler you can only continue when said module is available, this function indicates you may continue compilation without said module.

If it succeeds in loading the module, it returns `{:module, module}`. If not, returns `{:error, reason}` with the error reason. If the module being checked is currently in a compiler deadlock, this function returns `{:error, :unavailable}`. Unavailable doesn't necessarily mean the module doesn't exist, just that it is not currently available, but it (or may not) become available in the future.

Therefore, if you can only continue if the module is available, use `ensure_compiled!/1` instead. In particular, do not do this:

    case Code.ensure_compiled(module) do
      {:module, _} -> module
      {:error, _} -> raise ...
    end

See the module documentation for more information on code loading.

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# ensure_compiled!(module)

View Source (since 1.12.0)

    @spec ensure_compiled!(module()) :: module()

Ensures the given module is compiled and loaded.

If the module is already loaded, it works as no-op. If the module was not compiled yet, `ensure_compiled!/1` halts the compilation of the caller until the module given to `ensure_compiled!/1` becomes available or all files for the current project have been compiled. If compilation finishes and the module is not available or is in a deadlock, an error is raised.

Given this function halts compilation, use it carefully. In particular, avoid using it to guess which modules are in the system. Overuse of this function can also lead to deadlocks, where two modules check at the same time if the other is compiled. This returns a specific unavailable error code, where we cannot successfully verify a module is available or not.

See the module documentation for more information on code loading.

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# ensure_loaded(module)

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    @spec ensure_loaded(module()) ::
      {:module, module()}
      | {:error, :embedded | :badfile | :nofile | :on_load_failure}

Ensures the given module is loaded.

If the module is already loaded, this works as no-op. If the module was not yet loaded, it tries to load it.

If it succeeds in loading the module, it returns `{:module, module}`. If not, returns `{:error, reason}` with the error reason.

See the module documentation for more information on code loading.

## Examples

    iex> Code.ensure_loaded(Atom)
    {:module, Atom}

    iex> Code.ensure_loaded(DoesNotExist)
    {:error, :nofile}

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# ensure_loaded!(module)

View Source (since 1.12.0)

    @spec ensure_loaded!(module()) :: module()

Same as `ensure_loaded/1` but raises if the module cannot be loaded.

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# ensure_loaded?(module)

View Source

    @spec ensure_loaded?(module()) :: boolean()

Ensures the given module is loaded.

Similar to `ensure_loaded/1`, but returns `true` if the module is already loaded or was successfully loaded. Returns `false` otherwise.

## Examples

    iex> Code.ensure_loaded?(String)
    true

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# env_for_eval(env_or_opts)

View Source (since 1.14.0)

Returns an environment for evaluation.

It accepts either a `Macro.Env`, that is then pruned and prepared, or a list of options. It returns an environment that is ready for evaluation.

Most functions in this module will automatically prepare the given environment for evaluation, so you don't need to explicitly call this function, with the exception of `eval_quoted_with_env/3`, which was designed precisely to be called in a loop, to implement features such as interactive shells or anything else with multiple evaluations.

## Options

If an env is not given, the options can be:

- `:file` - the file to be considered in the evaluation

- `:line` - the line on which the script starts

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# eval_file(file, relative_to \\ nil)

View Source

    @spec eval_file(binary(), nil | binary()) :: {term(), binding()}

Evaluates the given file.

Accepts `relative_to` as an argument to tell where the file is located.

While `require_file/2` and `compile_file/2` return the loaded modules and their bytecode, `eval_file/2` simply evaluates the file contents and returns the evaluation result and its binding (exactly the same return value as `eval_string/3`).

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# eval_quoted(quoted, binding \\ [], env_or_opts \\ [])

View Source

    @spec eval_quoted(Macro.t(), binding(), Macro.Env.t() | keyword()) ::
      {term(), binding()}

Evaluates the quoted contents.

Warning: Calling this function inside a macro is considered bad practice as it will attempt to evaluate runtime values at compile time. Macro arguments are typically transformed by unquoting them into the returned quoted expressions (instead of evaluated).

See `eval_string/3` for a description of `binding` and `opts`.

## Examples

    iex> contents = quote(do: var!(a) + var!(b))
    iex> {result, binding} = Code.eval_quoted(contents, [a: 1, b: 2], file: __ENV__.file, line: __ENV__.line)
    iex> result
    3
    iex> Enum.sort(binding)
    [a: 1, b: 2]

For convenience, you can pass `__ENV__/0` as the `opts` argument and all options will be automatically extracted from the current environment:

    iex> contents = quote(do: var!(a) + var!(b))
    iex> {result, binding} = Code.eval_quoted(contents, [a: 1, b: 2], __ENV__)
    iex> result
    3
    iex> Enum.sort(binding)
    [a: 1, b: 2]

Link to this function

# eval_quoted_with_env(quoted, binding, env, opts \\ [])

View Source (since 1.14.0)

    @spec eval_quoted_with_env(Macro.t(), binding(), Macro.Env.t(), keyword()) ::
      {term(), binding(), Macro.Env.t()}

Evaluates the given `quoted` contents with `binding` and `env`.

This function is meant to be called in a loop, to implement features such as interactive shells or anything else with multiple evaluations. Therefore, the first time you call this function, you must compute the initial environment with `env_for_eval/1`. The remaining calls must pass the environment that was returned by this function.

## Options

- `:prune_binding` - (since v1.14.2) prune binding to keep only variables read or written by the evaluated code. Note that variables used by modules are always pruned, even if later used by the modules. You can submit to the `:on_module` tracer event and access the variables used by the module from its environment.

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# eval_string(string, binding \\ [], opts \\ [])

View Source

    @spec eval_string(List.Chars.t(), binding(), Macro.Env.t() | keyword()) ::
      {term(), binding()}

Evaluates the contents given by `string`.

The `binding` argument is a list of all variables and their values. The `opts` argument is a keyword list of environment options.

Warning: `string` can be any Elixir code and will be executed with the same privileges as the Erlang VM: this means that such code could compromise the machine (for example by executing system commands). Don't use `eval_string/3` with untrusted input (such as strings coming from the network).

## Options

Options can be:

- `:file` - the file to be considered in the evaluation

- `:line` - the line on which the script starts

Additionally, you may also pass an environment as second argument, so the evaluation happens within that environment.

Returns a tuple of the form `{value, binding}`, where `value` is the value returned from evaluating `string`. If an error occurs while evaluating `string`, an exception will be raised.

`binding` is a list with all variable names and their values after evaluating `string`. The binding keys are usually atoms, but they may be a tuple for variables defined in a different context. The names are in no particular order.

## Examples

    iex> {result, binding} = Code.eval_string("a + b", [a: 1, b: 2], file: __ENV__.file, line: __ENV__.line)
    iex> result
    3
    iex> Enum.sort(binding)
    [a: 1, b: 2]

    iex> {result, binding} = Code.eval_string("c = a + b", [a: 1, b: 2], __ENV__)
    iex> result
    3
    iex> Enum.sort(binding)
    [a: 1, b: 2, c: 3]

    iex> {result, binding} = Code.eval_string("a = a + b", [a: 1, b: 2])
    iex> result
    3
    iex> Enum.sort(binding)
    [a: 3, b: 2]

For convenience, you can pass `__ENV__/0` as the `opts` argument and all imports, requires and aliases defined in the current environment will be automatically carried over:

    iex> {result, binding} = Code.eval_string("a + b", [a: 1, b: 2], __ENV__)
    iex> result
    3
    iex> Enum.sort(binding)
    [a: 1, b: 2]

Link to this function

# fetch_docs(module_or_path)

View Source (since 1.7.0)

    @spec fetch_docs(module() | String.t()) ::
      {:docs_v1, annotation, beam_language, format, module_doc :: doc_content,
       metadata, docs :: [doc_element]}
      | {:error, :module_not_found | :chunk_not_found | {:invalid_chunk, binary()}}
    when annotation: :erl_anno.anno(),
         beam_language: :elixir | :erlang | atom(),
         doc_content: %{optional(binary()) => binary()} | :none | :hidden,
         doc_element:
           {{kind :: atom(), function_name :: atom(), arity()}, annotation,
            signature, doc_content, metadata},
         format: binary(),
         signature: [binary()],
         metadata: map()

Returns the docs for the given module or path to `.beam` file.

When given a module name, it finds its BEAM code and reads the docs from it.

When given a path to a `.beam` file, it will load the docs directly from that file.

It returns the term stored in the documentation chunk in the format defined by EEP 48 or `{:error, reason}` if the chunk is not available.

## Examples

    # Module documentation of an existing module
    iex> {:docs_v1, _, :elixir, _, %{"en" => module_doc}, _, _} = Code.fetch_docs(Atom)
    iex> module_doc |> String.split("\n") |> Enum.at(0)
    "Atoms are constants whose values are their own name."

    # A module that doesn't exist
    iex> Code.fetch_docs(ModuleNotGood)
    {:error, :module_not_found}

Link to this function

# format_file!(file, opts \\ [])

View Source (since 1.6.0)

    @spec format_file!(
      binary(),
      keyword()
    ) :: iodata()

Formats a file.

See `format_string!/2` for more information on code formatting and available options.

Link to this function

# format_string!(string, opts \\ [])

View Source (since 1.6.0)

    @spec format_string!(
      binary(),
      keyword()
    ) :: iodata()

Formats the given code `string`.

The formatter receives a string representing Elixir code and returns iodata representing the formatted code according to pre-defined rules.

## Options

- `:file` - the file which contains the string, used for error reporting

- `:line` - the line the string starts, used for error reporting

- `:line_length` - the line length to aim for when formatting the document. Defaults to 98. Note this value is used as guideline but there are situations where it is not enforced. See the "Line length" section below for more information

- `:locals_without_parens` - a keyword list of name and arity pairs that should be kept without parens whenever possible. The arity may be the atom `:*`, which implies all arities of that name. The formatter already includes a list of functions and this option augments this list.

- `:force_do_end_blocks` (since v1.9.0) - when `true`, converts all inline usages of `do: ...`, `else: ...` and friends into `do`-`end` blocks. Defaults to `false`. Note that this option is convergent: once you set it to `true`, all keywords will be converted. If you set it to `false` later on, `do`-`end` blocks won't be converted back to keywords.

- `:normalize_bitstring_modifiers` (since v1.14.0) - when `true`, removes unnecessary parentheses in known bitstring modifiers, for example `<<foo::binary()>>` becomes `<<foo::binary>>`, or adds parentheses for custom modifiers, where `<<foo::custom_type>>` becomes `<<foo::custom_type()>>`. Defaults to `true`. This option changes the AST.

- `:normalize_charlists_as_sigils` (since v1.15.0) - when `true`, formats charlists as `~c` sigils, for example `'foo'` becomes `~c"foo"`. Defaults to `true`. This option changes the AST.

## Design principles

The formatter was designed under three principles.

First, the formatter never changes the semantics of the code. This means the input AST and the output AST are almost always equivalent. The only cases where the formatter will change the AST is when the input AST would cause compiler warnings and the output AST won't. The cases where the formatter changes the AST can be disabled through formatting options if desired.

The second principle is to provide as little configuration as possible. This eases the formatter adoption by removing contention points while making sure a single style is followed consistently by the community as a whole.

The formatter does not hard code names. The formatter will not behave specially because a function is named `defmodule`, `def`, or the like. This principle mirrors Elixir's goal of being an extensible language where developers can extend the language with new constructs as if they were part of the language. When it is absolutely necessary to change behaviour based on the name, this behaviour should be configurable, such as the `:locals_without_parens` option.

## Running the formatter

The formatter attempts to fit the most it can on a single line and introduces line breaks wherever possible when it cannot.

In some cases, this may lead to undesired formatting. Therefore, some code generated by the formatter may not be aesthetically pleasing and may require explicit intervention from the developer. That's why we do not recommend to run the formatter blindly in an existing codebase. Instead you should format and sanity check each formatted file.

For example, the formatter may break a long function definition over multiple clauses:

    def my_function(
      %User{name: name, age: age, ...},
      arg1,
      arg2
    ) do
      ...
    end

While the code above is completely valid, you may prefer to match on the struct variables inside the function body in order to keep the definition on a single line:

    def my_function(%User{} = user, arg1, arg2) do
      %{name: name, age: age, ...} = user
      ...
    end

In some situations, you can use the fact the formatter does not generate elegant code as a hint for refactoring. Take this code:

    def board?(board_id, %User{} = user, available_permissions, required_permissions) do
      Tracker.OrganizationMembers.user_in_organization?(user.id, board.organization_id) and
        required_permissions == Enum.to_list(MapSet.intersection(MapSet.new(required_permissions), MapSet.new(available_permissions)))
    end

The code above has very long lines and running the formatter is not going to address this issue. In fact, the formatter may make it more obvious that you have complex expressions:

    def board?(board_id, %User{} = user, available_permissions, required_permissions) do
      Tracker.OrganizationMembers.user_in_organization?(user.id, board.organization_id) and
        required_permissions ==
          Enum.to_list(
            MapSet.intersection(
              MapSet.new(required_permissions),
              MapSet.new(available_permissions)
            )
          )
    end

Take such cases as a suggestion that your code should be refactored:

    def board?(board_id, %User{} = user, available_permissions, required_permissions) do
      Tracker.OrganizationMembers.user_in_organization?(user.id, board.organization_id) and
        matching_permissions?(required_permissions, available_permissions)
    end

    defp matching_permissions?(required_permissions, available_permissions) do
      intersection =
        required_permissions
        |> MapSet.new()
        |> MapSet.intersection(MapSet.new(available_permissions))
        |> Enum.to_list()

      required_permissions == intersection
    end

To sum it up: since the formatter cannot change the semantics of your code, sometimes it is necessary to tweak or refactor the code to get optimal formatting. To help better understand how to control the formatter, we describe in the next sections the cases where the formatter keeps the user encoding and how to control multiline expressions.

## Line length

Another point about the formatter is that the `:line_length` configuration is a guideline. In many cases, it is not possible for the formatter to break your code apart, which means it will go over the line length. For example, if you have a long string:

    "this is a very long string that will go over the line length"

The formatter doesn't know how to break it apart without changing the code underlying syntax representation, so it is up to you to step in:

    "this is a very long string " <>
       "that will go over the line length"

The string concatenation makes the code fit on a single line and also gives more options to the formatter.

This may also appear in do/end blocks, where the `do` keyword (or `->`) may go over the line length because there is no opportunity for the formatter to introduce a line break in a readable way. For example, if you do:

    case very_long_expression() do
    end

And only the `do` keyword is above the line length, Elixir will not emit this:

    case very_long_expression()
    do
    end

So it prefers to not touch the line at all and leave `do` above the line limit.

## Keeping user's formatting

The formatter respects the input format in some cases. Those are listed below:

- Insignificant digits in numbers are kept as is. The formatter, however, always inserts underscores for decimal numbers with more than 5 digits and converts hexadecimal digits to uppercase

- Strings, charlists, atoms and sigils are kept as is. No character is automatically escaped or unescaped. The choice of delimiter is also respected from the input

- Newlines inside blocks are kept as in the input except for:

  1. expressions that take multiple lines will always have an empty line before and after and 2) empty lines are always squeezed together into a single empty line

- The choice between `:do` keyword and `do`-`end` blocks is left to the user

- Lists, tuples, bitstrings, maps, structs and function calls will be broken into multiple lines if they are followed by a newline in the opening bracket and preceded by a new line in the closing bracket

- Newlines before certain operators (such as the pipeline operators) and before other operators (such as comparison operators)

The behaviours above are not guaranteed. We may remove or add new rules in the future. The goal of documenting them is to provide better understanding on what to expect from the formatter.

### Multi-line lists, maps, tuples, and the like

You can force lists, tuples, bitstrings, maps, structs and function calls to have one entry per line by adding a newline after the opening bracket and a new line before the closing bracket lines. For example:

    [
      foo,
      bar
    ]

If there are no newlines around the brackets, then the formatter will try to fit everything on a single line, such that the snippet below

    [foo,
     bar]

will be formatted as

    [foo, bar]

You can also force function calls and keywords to be rendered on multiple lines by having each entry on its own line:

    defstruct name: nil,
              age: 0

The code above will be kept with one keyword entry per line by the formatter. To avoid that, just squash everything into a single line.

### Parens and no parens in function calls

Elixir has two syntaxes for function calls. With parens and no parens. By default, Elixir will add parens to all calls except for:

1. calls that have `do`-`end` blocks
2. local calls without parens where the name and arity of the local call is also listed under `:locals_without_parens` (except for calls with arity 0, where the compiler always require parens)

The choice of parens and no parens also affects indentation. When a function call with parens doesn't fit on the same line, the formatter introduces a newline around parens and indents the arguments with two spaces:

    some_call(
      arg1,
      arg2,
      arg3
    )

On the other hand, function calls without parens are always indented by the function call length itself, like this:

    some_call arg1,
              arg2,
              arg3

If the last argument is a data structure, such as maps and lists, and the beginning of the data structure fits on the same line as the function call, then no indentation happens, this allows code like this:

    Enum.reduce(some_collection, initial_value, fn element, acc ->
      # code
    end)

    some_function_without_parens %{
      foo: :bar,
      baz: :bat
    }

## Code comments

The formatter also handles code comments in a way to guarantee a space is always added between the beginning of the comment (#) and the next character.

The formatter also extracts all trailing comments to their previous line. For example, the code below

    hello #world

will be rewritten to

    # world
    hello

Because code comments are handled apart from the code representation (AST), there are some situations where code comments are seen as ambiguous by the code formatter. For example, the comment in the anonymous function below

    fn
      arg1 ->
        body1
        # comment

      arg2 ->
        body2
    end

and in this one

    fn
      arg1 ->
        body1

      # comment
      arg2 ->
        body2
    end

are considered equivalent (the nesting is discarded alongside most of user formatting). In such cases, the code formatter will always format to the latter.

## Newlines

The formatter converts all newlines in code from `\r\n` to `\n`.

Link to this function

# get_compiler_option(key)

View Source (since 1.10.0)

    @spec get_compiler_option(atom()) :: term()

Returns the value of a given compiler option.

For a description of all options, see `put_compiler_option/2`.

## Examples

    Code.get_compiler_option(:debug_info)
    #=> true

Link to this function

# loaded?(module)

View Source (since 1.15.0)

    @spec loaded?(module()) :: boolean()

Returns `true` if the module is loaded.

This function doesn't attempt to load the module. For such behaviour, `ensure_loaded?/1` can be used.

## Examples

    iex> Code.loaded?(Atom)
    true

    iex> Code.loaded?(NotYetLoaded)
    false

Link to this function

# prepend_path(path, opts \\ [])

View Source

    @spec prepend_path(Path.t(), [{:cache, boolean()}]) :: boolean()

Prepends a path to the Erlang VM code path list.

This is the list of directories the Erlang VM uses for finding module code. The list of files is managed per Erlang VM node.

The path is expanded with `Path.expand/1` before being prepended. It requires the path to exist. Returns a boolean indicating if the path was successfully added.

## Examples

    Code.prepend_path(".")
    #=> true

    Code.prepend_path("/does_not_exist")
    #=> false

## Options

- `:cache` - (since v1.15.0) when true, the code path is cached the first time it is traversed in order to reduce file system operations. It requires Erlang/OTP 26, otherwise it is a no-op.

Link to this function

# prepend_paths(paths, opts \\ [])

View Source (since 1.15.0)

    @spec prepend_paths([Path.t()], [{:cache, boolean()}]) :: :ok

Prepends a list of `paths` to the Erlang VM code path list.

This is the list of directories the Erlang VM uses for finding module code. The list of files is managed per Erlang VM node.

All paths are expanded with `Path.expand/1` before being prepended. Only existing paths are prepended. This function always returns `:ok`, regardless of how many paths were prepended. Use `prepend_path/1` if you need more control.

## Examples

    Code.prepend_paths([".", "/does_not_exist"])
    #=> :ok

## Options

- `:cache` - when true, the code path is cached the first time it is traversed in order to reduce file system operations. It requires Erlang/OTP 26, otherwise it is a no-op.

Link to this function

# print_diagnostic(diagnostic, opts \\ [])

View Source (since 1.15.0)

    @spec print_diagnostic(
      diagnostic(:warning | :error),
      keyword()
    ) :: :ok

Prints a diagnostic into the standard error.

A diagnostic is either returned by `Kernel.ParallelCompiler` or by `Code.with_diagnostics/2`.

## Options

- `:snippet` - whether to read the code snippet in the diagnostic location. As it may impact performance, it is not recommended to be used in runtime. Defaults to `true`.

Link to this function

# purge_compiler_modules()

View Source (since 1.7.0)

    @spec purge_compiler_modules() :: {:ok, non_neg_integer()}

Purge compiler modules.

The compiler utilizes temporary modules to compile code. For example, `elixir_compiler_1`, `elixir_compiler_2`, and so on. In case the compiled code stores references to anonymous functions or similar, the Elixir compiler may be unable to reclaim those modules, keeping an unnecessary amount of code in memory and eventually leading to modules such as `elixir_compiler_12345`.

This function purges all modules currently kept by the compiler, allowing old compiler module names to be reused. If there are any processes running any code from such modules, they will be terminated too.

This function is only meant to be called if you have a long running node that is constantly evaluating code.

It returns `{:ok, number_of_modules_purged}`.

Link to this function

# put_compiler_option(key, value)

View Source (since 1.10.0)

    @spec put_compiler_option(atom(), term()) :: :ok

Stores a compilation option.

Changing the compilation options affect all processes running in a given Erlang VM node.

Available options are:

- `:docs` - when `true`, retains documentation in the compiled module. Defaults to `true`.

- `:debug_info` - when `true`, retains debug information in the compiled module. Defaults to `true`. This enables static analysis tools as it allows developers to partially reconstruct the original source code. Therefore, disabling `:debug_info` is not recommended as it removes the ability of the Elixir compiler and other tools to provide feedback. If you want to remove the `:debug_info` while deploying, tools like `mix release` already do such by default. Additionally, `mix test` disables it via the `:test_elixirc_options` project configuration option. This option can also be overridden per module using the `@compile` directive.

- `:ignore_already_consolidated` (since v1.10.0) - when `true`, does not warn when a protocol has already been consolidated and a new implementation is added. Defaults to `false`.

- `:ignore_module_conflict` - when `true`, does not warn when a module has already been defined. Defaults to `false`.

- `:relative_paths` - when `true`, uses relative paths in quoted nodes, warnings, and errors generated by the compiler. Note disabling this option won't affect runtime warnings and errors. Defaults to `true`.

- `:warnings_as_errors` - causes compilation to fail when warnings are generated. Defaults to `false`.

- `:no_warn_undefined` (since v1.10.0) - list of modules and `{Mod, fun, arity}` tuples that will not emit warnings that the module or function does not exist at compilation time. Pass atom `:all` to skip warning for all undefined functions. This can be useful when doing dynamic compilation. Defaults to `[]`.

- `:tracers` (since v1.10.0) - a list of tracers (modules) to be used during compilation. See the module docs for more information. Defaults to `[]`.

- `:parser_options` (since v1.10.0) - a keyword list of options to be given to the parser when compiling files. It accepts the same options as `string_to_quoted/2` (except by the options that change the AST itself). This can be used in combination with the tracer to retrieve localized information about events happening during compilation. Defaults to `[columns: true]`. This option only affects code compilation functions, such as `compile_string/2` and `compile_file/2` but not `string_to_quoted/2` and friends, as the latter is used for other purposes beyond compilation.

- `:on_undefined_variable` (since v1.15.0) - either `:raise` or `:warn`. When `:raise` (the default), undefined variables will trigger a compilation error. You may be set it to `:warn` if you want undefined variables to emit a warning and expand as to a local call to the zero-arity function of the same name (for example, `node` would be expanded as `node()`). This `:warn` behaviour only exists for compatibility reasons when working with old dependencies.

It always returns `:ok`. Raises an error for invalid options.

## Examples

    Code.put_compiler_option(:debug_info, true)
    #=> :ok

Link to this function

# quoted_to_algebra(quoted, opts \\ [])

View Source (since 1.13.0)

    @spec quoted_to_algebra(
      Macro.t(),
      keyword()
    ) :: Inspect.Algebra.t()

Converts a quoted expression to an algebra document using Elixir's formatter rules.

The algebra document can be converted into a string by calling:

    doc
    |> Inspect.Algebra.format(:infinity)
    |> IO.iodata_to_binary()

For a high-level function that does the same, see `Macro.to_string/1`.

## Formatting considerations

The Elixir AST does not contain metadata for literals like strings, lists, or tuples with two elements, which means that the produced algebra document will not respect all of the user preferences and comments may be misplaced. To get better results, you can use the `:token_metadata`, `:unescape` and `:literal_encoder` options to `string_to_quoted/2` to provide additional information to the formatter:

    [
      literal_encoder: &{:ok, {:__block__, &2, [&1]}},
      token_metadata: true,
      unescape: false
    ]

This will produce an AST that contains information such as `do` blocks start and end lines or sigil delimiters, and by wrapping literals in blocks they can now hold metadata like line number, string delimiter and escaped sequences, or integer formatting (such as `0x2a` instead of `47`). However, note this AST is not valid. If you evaluate it, it won't have the same semantics as the regular Elixir AST due to the `:unescape` and `:literal_encoder` options. However, those options are useful if you're doing source code manipulation, where it's important to preserve user choices and comments placing.

## Options

- `:comments` - the list of comments associated with the quoted expression. Defaults to `[]`. It is recommended that both `:token_metadata` and `:literal_encoder` options are given to `string_to_quoted_with_comments/2` in order to get proper placement for comments

- `:escape` - when `true`, escaped sequences like `\n` will be escaped into `\\n`. If the `:unescape` option was set to `false` when using `string_to_quoted/2`, setting this option to `false` will prevent it from escaping the sequences twice. Defaults to `true`.

- `:locals_without_parens` - a keyword list of name and arity pairs that should be kept without parens whenever possible. The arity may be the atom `:*`, which implies all arities of that name. The formatter already includes a list of functions and this option augments this list.

- `:syntax_colors` - a keyword list of colors the output is colorized. See `Inspect.Opts` for more information.

Link to this function

# require_file(file, relative_to \\ nil)

View Source

    @spec require_file(binary(), nil | binary()) :: [{module(), binary()}] | nil

Requires the given `file`.

Accepts `relative_to` as an argument to tell where the file is located. If the file was already required, `require_file/2` doesn't do anything and returns `nil`.

Note that if `require_file/2` is invoked by different processes concurrently, the first process to invoke `require_file/2` acquires a lock and the remaining ones will block until the file is available. This means that if `require_file/2` is called more than once with a given file, that file will be compiled only once. The first process to call `require_file/2` will get the list of loaded modules, others will get `nil`. The list of required files is managed per Erlang VM node.

See `compile_file/2` if you would like to compile a file without tracking its filenames. Finally, if you would like to get the result of evaluating a file rather than the modules defined in it, see `eval_file/2`.

## Examples

If the file has not been required, it returns the list of modules:

    modules = Code.require_file("eex_test.exs", "../eex/test")
    List.first(modules)
    #=> {EExTest.Compiled, <<70, 79, 82, 49, ...>>}

If the file has been required, it returns `nil`:

    Code.require_file("eex_test.exs", "../eex/test")
    #=> nil

Link to this function

# required_files()

View Source (since 1.7.0)

    @spec required_files() :: [binary()]

Lists all required files.

## Examples

    Code.require_file("../eex/test/eex_test.exs")
    List.first(Code.required_files()) =~ "eex_test.exs"
    #=> true

Link to this function

# string_to_quoted(string, opts \\ [])

View Source

    @spec string_to_quoted(
      List.Chars.t(),
      keyword()
    ) ::
      {:ok, Macro.t()}
      | {:error, {location :: keyword(), binary() | {binary(), binary()}, binary()}}

Converts the given string to its quoted form.

Returns `{:ok, quoted_form}` if it succeeds, `{:error, {meta, message_info, token}}` otherwise.

## Options

- `:file` - the filename to be reported in case of parsing errors. Defaults to `"nofile"`.

- `:line` - the starting line of the string being parsed. Defaults to 1.

- `:column` - (since v1.11.0) the starting column of the string being parsed. Defaults to 1.

- `:columns` - when `true`, attach a `:column` key to the quoted metadata. Defaults to `false`.

- `:unescape` (since v1.10.0) - when `false`, preserves escaped sequences. For example, `"null byte\\t\\x00"` will be kept as is instead of being converted to a bitstring literal. Note if you set this option to false, the resulting AST is no longer valid, but it can be useful to analyze/transform source code, typically in in combination with `quoted_to_algebra/2`. Defaults to `true`.

- `:existing_atoms_only` - when `true`, raises an error when non-existing atoms are found by the tokenizer. Defaults to `false`.

- `:token_metadata` (since v1.10.0) - when `true`, includes token-related metadata in the expression AST, such as metadata for `do` and `end` tokens, for closing tokens, end of expressions, as well as delimiters for sigils. See `Macro.metadata/0`. Defaults to `false`.

- `:literal_encoder` (since v1.10.0) - how to encode literals in the AST. It must be a function that receives two arguments, the literal and its metadata, and it must return `{:ok, ast :: Macro.t}` or `{:error, reason :: binary}`. If you return anything than the literal itself as the `term`, then the AST is no longer valid. This option may still useful for textual analysis of the source code.

- `:static_atoms_encoder` - the static atom encoder function, see "The `:static_atoms_encoder` function" section below. Note this option overrides the `:existing_atoms_only` behaviour for static atoms but `:existing_atoms_only` is still used for dynamic atoms, such as atoms with interpolations.

- `:emit_warnings` (since v1.16.0) - when `false`, does not emit tokenizing/parsing related warnings. Defaults to `true`.

## `Macro.to_string/2`

The opposite of converting a string to its quoted form is `Macro.to_string/2`, which converts a quoted form to a string/binary representation.

## The `:static_atoms_encoder` function

When `static_atoms_encoder: &my_encoder/2` is passed as an argument, `my_encoder/2` is called every time the tokenizer needs to create a "static" atom. Static atoms are atoms in the AST that function as aliases, remote calls, local calls, variable names, regular atoms and keyword lists.

The encoder function will receive the atom name (as a binary) and a keyword list with the current file, line and column. It must return `{:ok, token :: term} | {:error, reason :: binary}`.

The encoder function is supposed to create an atom from the given string. To produce a valid AST, it is required to return `{:ok, term}`, where `term` is an atom. It is possible to return something other than an atom, however, in that case the AST is no longer "valid" in that it cannot be used to compile or evaluate Elixir code. A use case for this is if you want to use the Elixir parser in a user-facing situation, but you don't want to exhaust the atom table.

The atom encoder is not called for all atoms that are present in the AST. It won't be invoked for the following atoms:

- operators (`:+`, `:-`, and so on)

- syntax keywords (`fn`, `do`, `else`, and so on)

- atoms containing interpolation (`:"#{1 + 1} is two"`), as these atoms are constructed at runtime

- atoms used to represent single-letter sigils like `:sigil_X` (but multi-letter sigils like `:sigil_XYZ` are encoded).

Link to this function

# string_to_quoted!(string, opts \\ [])

View Source

    @spec string_to_quoted!(
      List.Chars.t(),
      keyword()
    ) :: Macro.t()

Converts the given string to its quoted form.

It returns the AST if it succeeds, raises an exception otherwise. The exception is a `TokenMissingError` in case a token is missing (usually because the expression is incomplete), `SyntaxError` otherwise.

Check `string_to_quoted/2` for options information.

Link to this function

# string_to_quoted_with_comments(string, opts \\ [])

View Source (since 1.13.0)

    @spec string_to_quoted_with_comments(
      List.Chars.t(),
      keyword()
    ) ::
      {:ok, Macro.t(), [map()]} | {:error, {location :: keyword(), term(), term()}}

Converts the given string to its quoted form and a list of comments.

This function is useful when performing textual changes to the source code, while preserving information like comments and literals position.

Returns `{:ok, quoted_form, comments}` if it succeeds, `{:error, {line, error, token}}` otherwise.

Comments are maps with the following fields:

- `:line` - The line number the source code

- `:text` - The full text of the comment, including the leading `#`

- `:previous_eol_count` - How many end of lines there are between the comment and the previous AST node or comment

- `:next_eol_count` - How many end of lines there are between the comment and the next AST node or comment

Check `string_to_quoted/2` for options information.

## Examples

    iex> Code.string_to_quoted_with_comments("""
    ...> :foo
    ...>
    ...> # Hello, world!
    ...>
    ...>
    ...> # Some more comments!
    ...> """)
    {:ok, :foo, [
      %{line: 3, column: 1, previous_eol_count: 2, next_eol_count: 3, text: "# Hello, world!"},
      %{line: 6, column: 1, previous_eol_count: 3, next_eol_count: 1, text: "# Some more comments!"},
    ]}

    iex> Code.string_to_quoted_with_comments(":foo # :bar")
    {:ok, :foo, [
      %{line: 1, column: 6, previous_eol_count: 0, next_eol_count: 0, text: "# :bar"}
    ]}

Link to this function

# string_to_quoted_with_comments!(string, opts \\ [])

View Source (since 1.13.0)

    @spec string_to_quoted_with_comments!(
      List.Chars.t(),
      keyword()
    ) :: {Macro.t(), [map()]}

Converts the given string to its quoted form and a list of comments.

Returns the AST and a list of comments if it succeeds, raises an exception otherwise. The exception is a `TokenMissingError` in case a token is missing (usually because the expression is incomplete), `SyntaxError` otherwise.

Check `string_to_quoted/2` for options information.

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# unrequire_files(files)

View Source (since 1.7.0)

    @spec unrequire_files([binary()]) :: :ok

Removes files from the required files list.

The modules defined in the file are not removed; calling this function only removes them from the list, allowing them to be required again.

The list of files is managed per Erlang VM node.

## Examples

    # Require EEx test code
    Code.require_file("../eex/test/eex_test.exs")

    # Now unrequire all files
    Code.unrequire_files(Code.required_files())

    # Note that modules are still available
    function_exported?(EExTest.Compiled, :before_compile, 0)
    #=> true

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# with_diagnostics(opts \\ [], fun)

View Source (since 1.15.0)

    @spec with_diagnostics(
      keyword(),
      (-> result)
    ) :: {result, [diagnostic(:warning | :error)]}
    when result: term()

Executes the given `fun` and capture all diagnostics.

Diagnostics are warnings and errors emitted during code evaluation or single-file compilation and by functions such as `IO.warn/2`.

If using `mix compile` or `Kernel.ParallelCompiler`, note they already capture and return diagnostics.

## Options

- `:log` - if the diagnostics should be logged as they happen. Defaults to `false`.

> #### Rescuing errors

> `with_diagnostics/2` does not automatically handle exceptions. You may capture them by adding a `try/1` in `fun`:

>     {result, all_errors_and_warnings} =
>       Code.with_diagnostics(fn ->
>         try do
>           {:ok, Code.compile_quoted(quoted)}
>         rescue
>           err -> {:error, err}
>         end
>       end)