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Hook Functions

Hook Functions — support for manipulating lists of hook functions

Types and Values

Includes

#include <glib.h>

Description

The GHookList, GHook and their related functions provide support for lists of hook functions. Functions can be added and removed from the lists, and the list of hook functions can be invoked.

Functions

GHookFinalizeFunc ()

void
(*GHookFinalizeFunc) (GHookList *hook_list,
                      GHook *hook);

Defines the type of function to be called when a hook in a list of hooks gets finalized.

Parameters

hook_list

a GHookList

 

hook

the hook in hook_list that gets finalized

 

GHookFunc ()

void
(*GHookFunc) (gpointer data);

Defines the type of a hook function that can be invoked by g_hook_list_invoke().

Parameters

data

the data field of the GHook is passed to the hook function here

 

GHookCheckFunc ()

gboolean
(*GHookCheckFunc) (gpointer data);

Defines the type of a hook function that can be invoked by g_hook_list_invoke_check().

Parameters

data

the data field of the GHook is passed to the hook function here

 

Returns

FALSE if the GHook should be destroyed


g_hook_list_init ()

void
g_hook_list_init (GHookList *hook_list,
                  guint hook_size);

Initializes a GHookList. This must be called before the GHookList is used.

Parameters

hook_list

a GHookList

 

hook_size

the size of each element in the GHookList, typically sizeof (GHook).

 

g_hook_list_invoke ()

void
g_hook_list_invoke (GHookList *hook_list,
                    gboolean may_recurse);

Calls all of the GHook functions in a GHookList.

Parameters

hook_list

a GHookList

 

may_recurse

TRUE if functions which are already running (e.g. in another thread) can be called. If set to FALSE, these are skipped

 

g_hook_list_invoke_check ()

void
g_hook_list_invoke_check (GHookList *hook_list,
                          gboolean may_recurse);

Calls all of the GHook functions in a GHookList. Any function which returns FALSE is removed from the GHookList.

Parameters

hook_list

a GHookList

 

may_recurse

TRUE if functions which are already running (e.g. in another thread) can be called. If set to FALSE, these are skipped

 

g_hook_list_marshal ()

void
g_hook_list_marshal (GHookList *hook_list,
                     gboolean may_recurse,
                     GHookMarshaller marshaller,
                     gpointer marshal_data);

Calls a function on each valid GHook.

Parameters

hook_list

a GHookList

 

may_recurse

TRUE if hooks which are currently running (e.g. in another thread) are considered valid. If set to FALSE, these are skipped

 

marshaller

the function to call for each GHook

 

marshal_data

data to pass to marshaller

 

GHookMarshaller ()

void
(*GHookMarshaller) (GHook *hook,
                    gpointer marshal_data);

Defines the type of function used by g_hook_list_marshal().

Parameters

hook

a GHook

 

marshal_data

user data

 

g_hook_list_marshal_check ()

void
g_hook_list_marshal_check (GHookList *hook_list,
                           gboolean may_recurse,
                           GHookCheckMarshaller marshaller,
                           gpointer marshal_data);

Calls a function on each valid GHook and destroys it if the function returns FALSE.

Parameters

hook_list

a GHookList

 

may_recurse

TRUE if hooks which are currently running (e.g. in another thread) are considered valid. If set to FALSE, these are skipped

 

marshaller

the function to call for each GHook

 

marshal_data

data to pass to marshaller

 

GHookCheckMarshaller ()

gboolean
(*GHookCheckMarshaller) (GHook *hook,
                         gpointer marshal_data);

Defines the type of function used by g_hook_list_marshal_check().

Parameters

hook

a GHook

 

marshal_data

user data

 

Returns

FALSE if hook should be destroyed


g_hook_list_clear ()

void
g_hook_list_clear (GHookList *hook_list);

Removes all the GHook elements from a GHookList.

Parameters

hook_list

a GHookList

 

g_hook_alloc ()

GHook *
g_hook_alloc (GHookList *hook_list);

Allocates space for a GHook and initializes it.

Parameters

hook_list

a GHookList

 

Returns

a new GHook


g_hook_append()

#define             g_hook_append( hook_list, hook )

Appends a GHook onto the end of a GHookList.

Parameters

hook_list

a GHookList

 

hook

the GHook to add to the end of hook_list

 

g_hook_prepend ()

void
g_hook_prepend (GHookList *hook_list,
                GHook *hook);

Prepends a GHook on the start of a GHookList.

Parameters

hook_list

a GHookList

 

hook

the GHook to add to the start of hook_list

 

g_hook_insert_before ()

void
g_hook_insert_before (GHookList *hook_list,
                      GHook *sibling,
                      GHook *hook);

Inserts a GHook into a GHookList, before a given GHook.

Parameters

hook_list

a GHookList

 

sibling

the GHook to insert the new GHook before.

[nullable]

hook

the GHook to insert

 

g_hook_insert_sorted ()

void
g_hook_insert_sorted (GHookList *hook_list,
                      GHook *hook,
                      GHookCompareFunc func);

Inserts a GHook into a GHookList, sorted by the given function.

Parameters

hook_list

a GHookList

 

hook

the GHook to insert

 

func

the comparison function used to sort the GHook elements

 

GHookCompareFunc ()

gint
(*GHookCompareFunc) (GHook *new_hook,
                     GHook *sibling);

Defines the type of function used to compare GHook elements in g_hook_insert_sorted().

Parameters

new_hook

the GHook being inserted

 

sibling

the GHook to compare with new_hook

 

Returns

a value <= 0 if new_hook should be before sibling


g_hook_compare_ids ()

gint
g_hook_compare_ids (GHook *new_hook,
                    GHook *sibling);

Compares the ids of two GHook elements, returning a negative value if the second id is greater than the first.

Parameters

new_hook

a GHook

 

sibling

a GHook to compare with new_hook

 

Returns

a value <= 0 if the id of sibling is >= the id of new_hook


g_hook_get ()

GHook *
g_hook_get (GHookList *hook_list,
            gulong hook_id);

Returns the GHook with the given id, or NULL if it is not found.

Parameters

hook_list

a GHookList

 

hook_id

a hook id

 

Returns

the GHook with the given id, or NULL if it is not found


g_hook_find ()

GHook *
g_hook_find (GHookList *hook_list,
             gboolean need_valids,
             GHookFindFunc func,
             gpointer data);

Finds a GHook in a GHookList using the given function to test for a match.

Parameters

hook_list

a GHookList

 

need_valids

TRUE if GHook elements which have been destroyed should be skipped

 

func

the function to call for each GHook, which should return TRUE when the GHook has been found

 

data

the data to pass to func

 

Returns

the found GHook or NULL if no matching GHook is found


GHookFindFunc ()

gboolean
(*GHookFindFunc) (GHook *hook,
                  gpointer data);

Defines the type of the function passed to g_hook_find().

Parameters

hook

a GHook

 

data

user data passed to g_hook_find_func()

 

Returns

TRUE if the required GHook has been found


g_hook_find_data ()

GHook *
g_hook_find_data (GHookList *hook_list,
                  gboolean need_valids,
                  gpointer data);

Finds a GHook in a GHookList with the given data.

Parameters

hook_list

a GHookList

 

need_valids

TRUE if GHook elements which have been destroyed should be skipped

 

data

the data to find

 

Returns

the GHook with the given data or NULL if no matching GHook is found


g_hook_find_func ()

GHook *
g_hook_find_func (GHookList *hook_list,
                  gboolean need_valids,
                  gpointer func);

Finds a GHook in a GHookList with the given function.

Parameters

hook_list

a GHookList

 

need_valids

TRUE if GHook elements which have been destroyed should be skipped

 

func

the function to find

 

Returns

the GHook with the given func or NULL if no matching GHook is found


g_hook_find_func_data ()

GHook *
g_hook_find_func_data (GHookList *hook_list,
                       gboolean need_valids,
                       gpointer func,
                       gpointer data);

Finds a GHook in a GHookList with the given function and data.

Parameters

hook_list

a GHookList

 

need_valids

TRUE if GHook elements which have been destroyed should be skipped

 

func

the function to find.

[not nullable]

data

the data to find

 

Returns

the GHook with the given func and data or NULL if no matching GHook is found


g_hook_first_valid ()

GHook *
g_hook_first_valid (GHookList *hook_list,
                    gboolean may_be_in_call);

Returns the first GHook in a GHookList which has not been destroyed. The reference count for the GHook is incremented, so you must call g_hook_unref() to restore it when no longer needed. (Or call g_hook_next_valid() if you are stepping through the GHookList.)

Parameters

hook_list

a GHookList

 

may_be_in_call

TRUE if hooks which are currently running (e.g. in another thread) are considered valid. If set to FALSE, these are skipped

 

Returns

the first valid GHook, or NULL if none are valid


g_hook_next_valid ()

GHook *
g_hook_next_valid (GHookList *hook_list,
                   GHook *hook,
                   gboolean may_be_in_call);

Returns the next GHook in a GHookList which has not been destroyed. The reference count for the GHook is incremented, so you must call g_hook_unref() to restore it when no longer needed. (Or continue to call g_hook_next_valid() until NULL is returned.)

Parameters

hook_list

a GHookList

 

hook

the current GHook

 

may_be_in_call

TRUE if hooks which are currently running (e.g. in another thread) are considered valid. If set to FALSE, these are skipped

 

Returns

the next valid GHook, or NULL if none are valid


G_HOOK_FLAGS()

#define G_HOOK_FLAGS(hook)		(G_HOOK (hook)->flags)

Gets the flags of a hook.

Parameters

hook

a GHook

 

G_HOOK()

#define G_HOOK(hook)			((GHook*) (hook))

Casts a pointer to a GHook*.

Parameters

hook

a pointer

 

G_HOOK_IS_VALID()

#define             G_HOOK_IS_VALID(hook)

Returns TRUE if the GHook is valid, i.e. it is in a GHookList, it is active and it has not been destroyed.

Parameters

hook

a GHook

 

Returns

TRUE if the GHook is valid


G_HOOK_ACTIVE()

#define             G_HOOK_ACTIVE(hook)

Returns TRUE if the GHook is active, which is normally the case until the GHook is destroyed.

Parameters

hook

a GHook

 

Returns

TRUE if the GHook is active


G_HOOK_IN_CALL()

#define             G_HOOK_IN_CALL(hook)

Returns TRUE if the GHook function is currently executing.

Parameters

hook

a GHook

 

Returns

TRUE if the GHook function is currently executing


G_HOOK_IS_UNLINKED()

#define             G_HOOK_IS_UNLINKED(hook)

Returns TRUE if the GHook is not in a GHookList.

Parameters

hook

a GHook

 

Returns

TRUE if the GHook is not in a GHookList


g_hook_ref ()

GHook *
g_hook_ref (GHookList *hook_list,
            GHook *hook);

Increments the reference count for a GHook.

Parameters

hook_list

a GHookList

 

hook

the GHook to increment the reference count of

 

Returns

the hook that was passed in (since 2.6)


g_hook_unref ()

void
g_hook_unref (GHookList *hook_list,
              GHook *hook);

Decrements the reference count of a GHook. If the reference count falls to 0, the GHook is removed from the GHookList and g_hook_free() is called to free it.

Parameters

hook_list

a GHookList

 

hook

the GHook to unref

 

g_hook_free ()

void
g_hook_free (GHookList *hook_list,
             GHook *hook);

Calls the GHookList finalize_hook function if it exists, and frees the memory allocated for the GHook.

Parameters

hook_list

a GHookList

 

hook

the GHook to free

 

g_hook_destroy ()

gboolean
g_hook_destroy (GHookList *hook_list,
                gulong hook_id);

Destroys a GHook, given its ID.

Parameters

hook_list

a GHookList

 

hook_id

a hook ID

 

Returns

TRUE if the GHook was found in the GHookList and destroyed


g_hook_destroy_link ()

void
g_hook_destroy_link (GHookList *hook_list,
                     GHook *hook);

Removes one GHook from a GHookList, marking it inactive and calling g_hook_unref() on it.

Parameters

hook_list

a GHookList

 

hook

the GHook to remove

 

Types and Values

struct GHookList

struct GHookList {
  gulong	    seq_id;
  guint		    hook_size : 16;
  guint		    is_setup : 1;
  GHook		   *hooks;
  gpointer	    dummy3;
  GHookFinalizeFunc finalize_hook;
  gpointer	    dummy[2];
};

The GHookList struct represents a list of hook functions.

Members

gulong seq_id;

the next free GHook id

 

guint hook_size : 16;

the size of the GHookList elements, in bytes

 

guint is_setup : 1;

1 if the GHookList has been initialized

 

GHook *hooks;

the first GHook element in the list

 

gpointer dummy3;

unused

 

GHookFinalizeFunc finalize_hook;

the function to call to finalize a GHook element. The default behaviour is to call the hooks destroy function

 

gpointer dummy[2];

unused

 

struct GHook

struct GHook {
  gpointer	 data;
  GHook		*next;
  GHook		*prev;
  guint		 ref_count;
  gulong	 hook_id;
  guint		 flags;
  gpointer	 func;
  GDestroyNotify destroy;
};

The GHook struct represents a single hook function in a GHookList.

Members

gpointer data;

data which is passed to func when this hook is invoked

 

GHook *next;

pointer to the next hook in the list

 

GHook *prev;

pointer to the previous hook in the list

 

guint ref_count;

the reference count of this hook

 

gulong hook_id;

the id of this hook, which is unique within its list

 

guint flags;

flags which are set for this hook. See GHookFlagMask for predefined flags

 

gpointer func;

the function to call when this hook is invoked. The possible signatures for this function are GHookFunc and GHookCheckFunc

 

GDestroyNotify destroy;

the default finalize_hook function of a GHookList calls this member of the hook that is being finalized

 

enum GHookFlagMask

Flags used internally in the GHook implementation.

Members

G_HOOK_FLAG_ACTIVE

set if the hook has not been destroyed

 

G_HOOK_FLAG_IN_CALL

set if the hook is currently being run

 

G_HOOK_FLAG_MASK

A mask covering all bits reserved for hook flags; see G_HOOK_FLAG_USER_SHIFT

 

G_HOOK_FLAG_USER_SHIFT

#define G_HOOK_FLAG_USER_SHIFT (4)

The position of the first bit which is not reserved for internal use be the GHook implementation, i.e. 1 << G_HOOK_FLAG_USER_SHIFT is the first bit which can be used for application-defined flags.

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