GObject.signal_has_handler_pending
Description: Reference for GObject.signal_has_handler_pending

### Function

# GObjectsignal_has_handler_pending

#### Declaration [src]

    gboolean
    g_signal_has_handler_pending (
      GObject* instance,
      guint signal_id,
      GQuark detail,
      gboolean may_be_blocked
    )

#### Description [src]

Returns whether there are any handlers connected to `instance` for the given signal id and detail.

If `detail` is 0 then it will only match handlers that were connected without detail. If `detail` is non-zero then it will match handlers connected both without detail and with the given detail. This is consistent with how a signal emitted with `detail` would be delivered to those handlers.

Since 2.46 this also checks for a non-default class closure being installed, as this is basically always what you want.

One example of when you might use this is when the arguments to the signal are difficult to compute. A class implementor may opt to not emit the signal if no one is attached anyway, thus saving the cost of building the arguments.

#### Parameters

`instance`

  Type: `GObject`

  The object whose signal handlers are sought.

  The data is owned by the caller of the function.

`signal_id`

  Type: `guint`

  The signal id.

`detail`

  Type: `GQuark`

  The detail.

`may_be_blocked`

  Type: `gboolean`

  Whether blocked handlers should count as match.

#### Return value

Type: `gboolean`

`TRUE` if a handler is connected to the signal, `FALSE` otherwise.