GI.Gio.Structs.IOExtensionPoint

GIOExtensionPoint provides a mechanism for modules to extend the functionality of the library or application that loaded it in an organized fashion.

An extension point is identified by a name, and it may optionally require that any implementation must be of a certain type (or derived thereof). Use iOExtensionPointRegister to register an extension point, and iOExtensionPointSetRequiredType to set a required type.

A module can implement an extension point by specifying the [typegObject.Type] that implements the functionality. Additionally, each implementation of an extension point has a name, and a priority. Use iOExtensionPointImplement to implement an extension point.

c code

GIOExtensionPoint *ep;

// Register an extension point
ep = g_io_extension_point_register ("my-extension-point");
g_io_extension_point_set_required_type (ep, MY_TYPE_EXAMPLE);

c code

// Implement an extension point
G_DEFINE_TYPE (MyExampleImpl, my_example_impl, MY_TYPE_EXAMPLE)
g_io_extension_point_implement ("my-extension-point",
                                my_example_impl_get_type (),
                                "my-example",
                                10);

It is up to the code that registered the extension point how it uses the implementations that have been associated with it. Depending on the use case, it may use all implementations, or only the one with the highest priority, or pick a specific one by name.

To avoid opening all modules just to find out what extension points they implement, GIO makes use of a caching mechanism, see gio-querymodules. You are expected to run this command after installing a GIO module.

The GIO_EXTRA_MODULES environment variable can be used to specify additional directories to automatically load modules from. This environment variable has the same syntax as the PATH. If two modules have the same base name in different directories, then the latter one will be ignored. If additional directories are specified GIO will load modules from the built-in directory last.

Exported types

newtype IOExtensionPoint

Memory-managed wrapper type.

Constructors

IOExtensionPoint (ManagedPtr IOExtensionPoint)

Instances

Eq IOExtensionPoint

Defined in GI.Gio.Structs.IOExtensionPoint

Methods

(==) :: IOExtensionPoint -> IOExtensionPoint -> Bool

(/=) :: IOExtensionPoint -> IOExtensionPoint -> Bool

BoxedPtr IOExtensionPoint

Defined in GI.Gio.Structs.IOExtensionPoint

Methods

boxedPtrCopy :: IOExtensionPoint -> IO IOExtensionPoint

boxedPtrFree :: IOExtensionPoint -> IO ()

ManagedPtrNewtype IOExtensionPoint

Defined in GI.Gio.Structs.IOExtensionPoint

Methods

toManagedPtr :: IOExtensionPoint -> ManagedPtr IOExtensionPoint

Methods

Click to display all available methods, including inherited ones

Methods

None.

Getters

getExtensionByName, getExtensions, getRequiredType.

Setters

setRequiredType.

getExtensionByName

iOExtensionPointGetExtensionByName

Arguments

:: (HasCallStack, MonadIO m)

=> IOExtensionPoint

extensionPoint: a IOExtensionPoint

-> Text

name: the name of the extension to get

-> m IOExtension

Returns: the IOExtension for extensionPoint that has the given name, or Nothing if there is no extension with that name

Finds a IOExtension for an extension point by name.

getExtensions

iOExtensionPointGetExtensions

Arguments

:: (HasCallStack, MonadIO m)

=> IOExtensionPoint

extensionPoint: a IOExtensionPoint

-> m [IOExtension]

Returns: a List of GIOExtensions. The list is owned by GIO and should not be modified.

Gets a list of all extensions that implement this extension point. The list is sorted by priority, beginning with the highest priority.

getRequiredType

iOExtensionPointGetRequiredType

Arguments

:: (HasCallStack, MonadIO m)

=> IOExtensionPoint

extensionPoint: a IOExtensionPoint

-> m GType

Returns: the GType that all implementations must have, or G_TYPE_INVALID if the extension point has no required type

Gets the required type for extensionPoint.

implement

iOExtensionPointImplement

Arguments

:: (HasCallStack, MonadIO m)

=> Text

extensionPointName: the name of the extension point

-> GType

type: the GType to register as extension

-> Text

extensionName: the name for the extension

-> Int32

priority: the priority for the extension

-> m IOExtension

Returns: a IOExtension object for GType

Registers type as extension for the extension point with name extensionPointName.

If type has already been registered as an extension for this extension point, the existing IOExtension object is returned.

lookup

iOExtensionPointLookup

Arguments

:: (HasCallStack, MonadIO m)

=> Text

name: the name of the extension point

-> m IOExtensionPoint

Returns: the IOExtensionPoint, or Nothing if there is no registered extension point with the given name.

Looks up an existing extension point.

register

iOExtensionPointRegister

Arguments

:: (HasCallStack, MonadIO m)

=> Text

name: The name of the extension point

-> m IOExtensionPoint

Returns: the new IOExtensionPoint. This object is owned by GIO and should not be freed.

Registers an extension point.

setRequiredType

iOExtensionPointSetRequiredType

Arguments

:: (HasCallStack, MonadIO m)

=> IOExtensionPoint

extensionPoint: a IOExtensionPoint

-> GType

type: the GType to require

-> m ()

Sets the required type for extensionPoint to type. All implementations must henceforth have this type.