glib/gobject/gclosure.c
changeset 18 47c74d1534e1
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/glib/gobject/gclosure.c	Fri Apr 16 16:46:38 2010 +0300
@@ -0,0 +1,1227 @@
+/* GObject - GLib Type, Object, Parameter and Signal Library
+ * Copyright (C) 2000-2001 Red Hat, Inc.
+ * Copyright (C) 2005 Imendio AB
+ * Portions copyright (c) 2006-2009 Nokia Corporation.  All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/*
+ * MT safe with regards to reference counting.
+ */
+
+#include "config.h"
+
+#include <string.h>
+
+#include "gclosure.h"
+#include "gvalue.h"
+#include "gobjectalias.h"
+
+
+/**
+ * SECTION:gclosure
+ * @short_description: Functions as first-class objects
+ * @title: Closures
+ *
+ * A #GClosure represents a callback supplied by the programmer. It
+ * will generally comprise a function of some kind and a marshaller
+ * used to call it. It is the reponsibility of the marshaller to
+ * convert the arguments for the invocation from #GValue<!-- -->s into
+ * a suitable form, perform the callback on the converted arguments,
+ * and transform the return value back into a #GValue.
+ *
+ * In the case of C programs, a closure usually just holds a pointer
+ * to a function and maybe a data argument, and the marshaller
+ * converts between #GValue<!-- --> and native C types. The GObject
+ * library provides the #GCClosure type for this purpose. Bindings for
+ * other languages need marshallers which convert between #GValue<!--
+ * -->s and suitable representations in the runtime of the language in
+ * order to use functions written in that languages as callbacks.
+ *
+ * Within GObject, closures play an important role in the
+ * implementation of signals. When a signal is registered, the
+ * @c_marshaller argument to g_signal_new() specifies the default C
+ * marshaller for any closure which is connected to this
+ * signal. GObject provides a number of C marshallers for this
+ * purpose, see the g_cclosure_marshal_*() functions. Additional C
+ * marshallers can be generated with the <link
+ * linkend="glib-genmarshal">glib-genmarshal</link> utility.  Closures
+ * can be explicitly connected to signals with
+ * g_signal_connect_closure(), but it usually more convenient to let
+ * GObject create a closure automatically by using one of the
+ * g_signal_connect_*() functions which take a callback function/user
+ * data pair.
+ *
+ * Using closures has a number of important advantages over a simple
+ * callback function/data pointer combination:
+ * <itemizedlist>
+ * <listitem><para>
+ * Closures allow the callee to get the types of the callback parameters,
+ * which means that language bindings don't have to write individual glue
+ * for each callback type.
+ * </para></listitem>
+ * <listitem><para>
+ * The reference counting of #GClosure makes it easy to handle reentrancy
+ * right; if a callback is removed while it is being invoked, the closure
+ * and its parameters won't be freed until the invocation finishes.
+ * </para></listitem>
+ * <listitem><para>
+ * g_closure_invalidate() and invalidation notifiers allow callbacks to be
+ * automatically removed when the objects they point to go away.
+ * </para></listitem>
+ * </itemizedlist>
+ */
+
+
+#define	CLOSURE_MAX_REF_COUNT		((1 << 15) - 1)
+#define	CLOSURE_MAX_N_GUARDS		((1 << 1) - 1)
+#define	CLOSURE_MAX_N_FNOTIFIERS	((1 << 2) - 1)
+#define	CLOSURE_MAX_N_INOTIFIERS	((1 << 8) - 1)
+#define	CLOSURE_N_MFUNCS(cl)		((cl)->meta_marshal + \
+                                         ((cl)->n_guards << 1L))
+/* same as G_CLOSURE_N_NOTIFIERS() (keep in sync) */
+#define	CLOSURE_N_NOTIFIERS(cl)		(CLOSURE_N_MFUNCS (cl) + \
+                                         (cl)->n_fnotifiers + \
+                                         (cl)->n_inotifiers)
+
+typedef union {
+  GClosure closure;
+  volatile gint vint;
+} ClosureInt;
+
+#define CHANGE_FIELD(_closure, _field, _OP, _value, _must_set, _SET_OLD, _SET_NEW)      \
+G_STMT_START {                                                                          \
+  ClosureInt *cunion = (ClosureInt*) _closure;                 		                \
+  gint new_int, old_int, success;                              		                \
+  do                                                    		                \
+    {                                                   		                \
+      ClosureInt tmp;                                   		                \
+      tmp.vint = old_int = cunion->vint;                		                \
+      _SET_OLD tmp.closure._field;                                                      \
+      tmp.closure._field _OP _value;                      		                \
+      _SET_NEW tmp.closure._field;                                                      \
+      new_int = tmp.vint;                               		                \
+      success = g_atomic_int_compare_and_exchange (&cunion->vint, old_int, new_int);    \
+    }                                                   		                \
+  while (!success && _must_set);                                                        \
+} G_STMT_END
+
+#define SWAP(_closure, _field, _value, _oldv)   CHANGE_FIELD (_closure, _field, =, _value, TRUE, *(_oldv) =,     (void) )
+#define SET(_closure, _field, _value)           CHANGE_FIELD (_closure, _field, =, _value, TRUE,     (void),     (void) )
+#define INC(_closure, _field)                   CHANGE_FIELD (_closure, _field, +=,     1, TRUE,     (void),     (void) )
+#define INC_ASSIGN(_closure, _field, _newv)     CHANGE_FIELD (_closure, _field, +=,     1, TRUE,     (void), *(_newv) = )
+#define DEC(_closure, _field)                   CHANGE_FIELD (_closure, _field, -=,     1, TRUE,     (void),     (void) )
+#define DEC_ASSIGN(_closure, _field, _newv)     CHANGE_FIELD (_closure, _field, -=,     1, TRUE,     (void), *(_newv) = )
+
+#if 0   /* for non-thread-safe closures */
+#define SWAP(cl,f,v,o)     (void) (*(o) = cl->f, cl->f = v)
+#define SET(cl,f,v)        (void) (cl->f = v)
+#define INC(cl,f)          (void) (cl->f += 1)
+#define INC_ASSIGN(cl,f,n) (void) (cl->f += 1, *(n) = cl->f)
+#define DEC(cl,f)          (void) (cl->f -= 1)
+#define DEC_ASSIGN(cl,f,n) (void) (cl->f -= 1, *(n) = cl->f)
+#endif
+
+enum {
+  FNOTIFY,
+  INOTIFY,
+  PRE_NOTIFY,
+  POST_NOTIFY
+};
+
+
+/* --- functions --- */
+/**
+ * g_closure_new_simple:
+ * @sizeof_closure: the size of the structure to allocate, must be at least
+ *                  <literal>sizeof (GClosure)</literal>
+ * @data: data to store in the @data field of the newly allocated #GClosure
+ *
+ * Allocates a struct of the given size and initializes the initial
+ * part as a #GClosure. This function is mainly useful when
+ * implementing new types of closures.
+ *
+ * |[
+ * typedef struct _MyClosure MyClosure;
+ * struct _MyClosure
+ * {
+ *   GClosure closure;
+ *   // extra data goes here
+ * };
+ *
+ * static void
+ * my_closure_finalize (gpointer  notify_data,
+ *                      GClosure *closure)
+ * {
+ *   MyClosure *my_closure = (MyClosure *)closure;
+ *
+ *   // free extra data here
+ * }
+ *
+ * MyClosure *my_closure_new (gpointer data)
+ * {
+ *   GClosure *closure;
+ *   MyClosure *my_closure;
+ *
+ *   closure = g_closure_new_simple (sizeof (MyClosure), data);
+ *   my_closure = (MyClosure *) closure;
+ *
+ *   // initialize extra data here
+ *
+ *   g_closure_add_finalize_notifier (closure, notify_data,
+ *                                    my_closure_finalize);
+ *   return my_closure;
+ * }
+ * ]|
+ *
+ * Returns: a newly allocated #GClosure
+ */
+EXPORT_C GClosure*
+g_closure_new_simple (guint           sizeof_closure,
+		      gpointer        data)
+{
+  GClosure *closure;
+
+  g_return_val_if_fail (sizeof_closure >= sizeof (GClosure), NULL);
+
+  closure = g_malloc0 (sizeof_closure);
+  SET (closure, ref_count, 1);
+  SET (closure, meta_marshal, 0);
+  SET (closure, n_guards, 0);
+  SET (closure, n_fnotifiers, 0);
+  SET (closure, n_inotifiers, 0);
+  SET (closure, in_inotify, FALSE);
+  SET (closure, floating, TRUE);
+  SET (closure, derivative_flag, 0);
+  SET (closure, in_marshal, FALSE);
+  SET (closure, is_invalid, FALSE);
+  closure->marshal = NULL;
+  closure->data = data;
+  closure->notifiers = NULL;
+  memset (G_STRUCT_MEMBER_P (closure, sizeof (*closure)), 0, sizeof_closure - sizeof (*closure));
+
+  return closure;
+}
+
+static inline void
+closure_invoke_notifiers (GClosure *closure,
+			  guint     notify_type)
+{
+  /* notifier layout:
+   *     meta_marshal  n_guards    n_guards     n_fnotif.  n_inotifiers
+   * ->[[meta_marshal][pre_guards][post_guards][fnotifiers][inotifiers]]
+   *
+   * CLOSURE_N_MFUNCS(cl)    = meta_marshal + n_guards + n_guards;
+   * CLOSURE_N_NOTIFIERS(cl) = CLOSURE_N_MFUNCS(cl) + n_fnotifiers + n_inotifiers
+   *
+   * constrains/catches:
+   * - closure->notifiers may be reloacted during callback
+   * - closure->n_fnotifiers and closure->n_inotifiers may change during callback
+   * - i.e. callbacks can be removed/added during invocation
+   * - must prepare for callback removal during FNOTIFY and INOTIFY (done via ->marshal= & ->data=)
+   * - must distinguish (->marshal= & ->data=) for INOTIFY vs. FNOTIFY (via ->in_inotify)
+   * + closure->n_guards is const during PRE_NOTIFY & POST_NOTIFY
+   * + closure->meta_marshal is const for all cases
+   * + none of the callbacks can cause recursion
+   * + closure->n_inotifiers is const 0 during FNOTIFY
+   */
+  switch (notify_type)
+    {
+      GClosureNotifyData *ndata;
+      guint i, offs;
+    case FNOTIFY:
+      while (closure->n_fnotifiers)
+	{
+          guint n;
+	  DEC_ASSIGN (closure, n_fnotifiers, &n);
+
+	  ndata = closure->notifiers + CLOSURE_N_MFUNCS (closure) + n;
+	  closure->marshal = (GClosureMarshal) ndata->notify;
+	  closure->data = ndata->data;
+	  ndata->notify (ndata->data, closure);
+	}
+      closure->marshal = NULL;
+      closure->data = NULL;
+      break;
+    case INOTIFY:
+      SET (closure, in_inotify, TRUE);
+      while (closure->n_inotifiers)
+	{
+          guint n;
+          DEC_ASSIGN (closure, n_inotifiers, &n);
+
+	  ndata = closure->notifiers + CLOSURE_N_MFUNCS (closure) + closure->n_fnotifiers + n;
+	  closure->marshal = (GClosureMarshal) ndata->notify;
+	  closure->data = ndata->data;
+	  ndata->notify (ndata->data, closure);
+	}
+      closure->marshal = NULL;
+      closure->data = NULL;
+      SET (closure, in_inotify, FALSE);
+      break;
+    case PRE_NOTIFY:
+      i = closure->n_guards;
+      offs = closure->meta_marshal;
+      while (i--)
+	{
+	  ndata = closure->notifiers + offs + i;
+	  ndata->notify (ndata->data, closure);
+	}
+      break;
+    case POST_NOTIFY:
+      i = closure->n_guards;
+      offs = closure->meta_marshal + i;
+      while (i--)
+	{
+	  ndata = closure->notifiers + offs + i;
+	  ndata->notify (ndata->data, closure);
+	}
+      break;
+    }
+}
+
+/**
+ * g_closure_set_meta_marshal:
+ * @closure: a #GClosure
+ * @marshal_data: context-dependent data to pass to @meta_marshal
+ * @meta_marshal: a #GClosureMarshal function
+ *
+ * Sets the meta marshaller of @closure.  A meta marshaller wraps
+ * @closure->marshal and modifies the way it is called in some
+ * fashion. The most common use of this facility is for C callbacks.
+ * The same marshallers (generated by <link
+ * linkend="glib-genmarshal">glib-genmarshal</link>) are used
+ * everywhere, but the way that we get the callback function
+ * differs. In most cases we want to use @closure->callback, but in
+ * other cases we want to use some different technique to retrieve the
+ * callback function.
+ *
+ * For example, class closures for signals (see
+ * g_signal_type_cclosure_new()) retrieve the callback function from a
+ * fixed offset in the class structure.  The meta marshaller retrieves
+ * the right callback and passes it to the marshaller as the
+ * @marshal_data argument.
+ */
+EXPORT_C void
+g_closure_set_meta_marshal (GClosure       *closure,
+			    gpointer        marshal_data,
+			    GClosureMarshal meta_marshal)
+{
+  GClosureNotifyData *notifiers;
+
+  g_return_if_fail (closure != NULL);
+  g_return_if_fail (meta_marshal != NULL);
+  g_return_if_fail (closure->is_invalid == FALSE);
+  g_return_if_fail (closure->in_marshal == FALSE);
+  g_return_if_fail (closure->meta_marshal == 0);
+
+  notifiers = closure->notifiers;
+  closure->notifiers = g_renew (GClosureNotifyData, NULL, CLOSURE_N_NOTIFIERS (closure) + 1);
+  if (notifiers)
+    {
+      /* usually the meta marshal will be setup right after creation, so the
+       * g_memmove() should be rare-case scenario
+       */
+      g_memmove (closure->notifiers + 1, notifiers, CLOSURE_N_NOTIFIERS (closure) * sizeof (notifiers[0]));
+      g_free (notifiers);
+    }
+  closure->notifiers[0].data = marshal_data;
+  closure->notifiers[0].notify = (GClosureNotify) meta_marshal;
+  SET (closure, meta_marshal, 1);
+}
+
+/**
+ * g_closure_add_marshal_guards:
+ * @closure: a #GClosure
+ * @pre_marshal_data: data to pass to @pre_marshal_notify
+ * @pre_marshal_notify: a function to call before the closure callback
+ * @post_marshal_data: data to pass to @post_marshal_notify
+ * @post_marshal_notify: a function to call after the closure callback
+ *
+ * Adds a pair of notifiers which get invoked before and after the
+ * closure callback, respectively. This is typically used to protect
+ * the extra arguments for the duration of the callback. See
+ * g_object_watch_closure() for an example of marshal guards.
+ */
+EXPORT_C void
+g_closure_add_marshal_guards (GClosure      *closure,
+			      gpointer       pre_marshal_data,
+			      GClosureNotify pre_marshal_notify,
+			      gpointer       post_marshal_data,
+			      GClosureNotify post_marshal_notify)
+{
+  guint i;
+
+  g_return_if_fail (closure != NULL);
+  g_return_if_fail (pre_marshal_notify != NULL);
+  g_return_if_fail (post_marshal_notify != NULL);
+  g_return_if_fail (closure->is_invalid == FALSE);
+  g_return_if_fail (closure->in_marshal == FALSE);
+  g_return_if_fail (closure->n_guards < CLOSURE_MAX_N_GUARDS);
+
+  closure->notifiers = g_renew (GClosureNotifyData, closure->notifiers, CLOSURE_N_NOTIFIERS (closure) + 2);
+  if (closure->n_inotifiers)
+    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+			closure->n_fnotifiers +
+			closure->n_inotifiers + 1)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+									  closure->n_fnotifiers + 0)];
+  if (closure->n_inotifiers > 1)
+    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+			closure->n_fnotifiers +
+			closure->n_inotifiers)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+								      closure->n_fnotifiers + 1)];
+  if (closure->n_fnotifiers)
+    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+			closure->n_fnotifiers + 1)] = closure->notifiers[CLOSURE_N_MFUNCS (closure) + 0];
+  if (closure->n_fnotifiers > 1)
+    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+			closure->n_fnotifiers)] = closure->notifiers[CLOSURE_N_MFUNCS (closure) + 1];
+  if (closure->n_guards)
+    closure->notifiers[(closure->meta_marshal +
+			closure->n_guards +
+			closure->n_guards + 1)] = closure->notifiers[closure->meta_marshal + closure->n_guards];
+  i = closure->n_guards;
+  closure->notifiers[closure->meta_marshal + i].data = pre_marshal_data;
+  closure->notifiers[closure->meta_marshal + i].notify = pre_marshal_notify;
+  closure->notifiers[closure->meta_marshal + i + 1].data = post_marshal_data;
+  closure->notifiers[closure->meta_marshal + i + 1].notify = post_marshal_notify;
+  INC (closure, n_guards);
+}
+
+/**
+ * g_closure_add_finalize_notifier:
+ * @closure: a #GClosure
+ * @notify_data: data to pass to @notify_func
+ * @notify_func: the callback function to register
+ *
+ * Registers a finalization notifier which will be called when the
+ * reference count of @closure goes down to 0. Multiple finalization
+ * notifiers on a single closure are invoked in unspecified order. If
+ * a single call to g_closure_unref() results in the closure being
+ * both invalidated and finalized, then the invalidate notifiers will
+ * be run before the finalize notifiers.
+ */
+EXPORT_C void
+g_closure_add_finalize_notifier (GClosure      *closure,
+				 gpointer       notify_data,
+				 GClosureNotify notify_func)
+{
+  guint i;
+
+  g_return_if_fail (closure != NULL);
+  g_return_if_fail (notify_func != NULL);
+  g_return_if_fail (closure->n_fnotifiers < CLOSURE_MAX_N_FNOTIFIERS);
+
+  closure->notifiers = g_renew (GClosureNotifyData, closure->notifiers, CLOSURE_N_NOTIFIERS (closure) + 1);
+  if (closure->n_inotifiers)
+    closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+			closure->n_fnotifiers +
+			closure->n_inotifiers)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+								      closure->n_fnotifiers + 0)];
+  i = CLOSURE_N_MFUNCS (closure) + closure->n_fnotifiers;
+  closure->notifiers[i].data = notify_data;
+  closure->notifiers[i].notify = notify_func;
+  INC (closure, n_fnotifiers);
+}
+
+/**
+ * g_closure_add_invalidate_notifier:
+ * @closure: a #GClosure
+ * @notify_data: data to pass to @notify_func
+ * @notify_func: the callback function to register
+ *
+ * Registers an invalidation notifier which will be called when the
+ * @closure is invalidated with g_closure_invalidate(). Invalidation
+ * notifiers are invoked before finalization notifiers, in an
+ * unspecified order.
+ */
+EXPORT_C void
+g_closure_add_invalidate_notifier (GClosure      *closure,
+				   gpointer       notify_data,
+				   GClosureNotify notify_func)
+{
+  guint i;
+
+  g_return_if_fail (closure != NULL);
+  g_return_if_fail (notify_func != NULL);
+  g_return_if_fail (closure->is_invalid == FALSE);
+  g_return_if_fail (closure->n_inotifiers < CLOSURE_MAX_N_INOTIFIERS);
+
+  closure->notifiers = g_renew (GClosureNotifyData, closure->notifiers, CLOSURE_N_NOTIFIERS (closure) + 1);
+  i = CLOSURE_N_MFUNCS (closure) + closure->n_fnotifiers + closure->n_inotifiers;
+  closure->notifiers[i].data = notify_data;
+  closure->notifiers[i].notify = notify_func;
+  INC (closure, n_inotifiers);
+}
+
+static inline gboolean
+closure_try_remove_inotify (GClosure       *closure,
+			    gpointer       notify_data,
+			    GClosureNotify notify_func)
+{
+  GClosureNotifyData *ndata, *nlast;
+
+  nlast = closure->notifiers + CLOSURE_N_NOTIFIERS (closure) - 1;
+  for (ndata = nlast + 1 - closure->n_inotifiers; ndata <= nlast; ndata++)
+    if (ndata->notify == notify_func && ndata->data == notify_data)
+      {
+	DEC (closure, n_inotifiers);
+	if (ndata < nlast)
+	  *ndata = *nlast;
+
+	return TRUE;
+      }
+  return FALSE;
+}
+
+static inline gboolean
+closure_try_remove_fnotify (GClosure       *closure,
+			    gpointer       notify_data,
+			    GClosureNotify notify_func)
+{
+  GClosureNotifyData *ndata, *nlast;
+
+  nlast = closure->notifiers + CLOSURE_N_NOTIFIERS (closure) - closure->n_inotifiers - 1;
+  for (ndata = nlast + 1 - closure->n_fnotifiers; ndata <= nlast; ndata++)
+    if (ndata->notify == notify_func && ndata->data == notify_data)
+      {
+	DEC (closure, n_fnotifiers);
+	if (ndata < nlast)
+	  *ndata = *nlast;
+	if (closure->n_inotifiers)
+	  closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+			      closure->n_fnotifiers)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +
+									    closure->n_fnotifiers +
+									    closure->n_inotifiers)];
+	return TRUE;
+      }
+  return FALSE;
+}
+
+/**
+ * g_closure_ref:
+ * @closure: #GClosure to increment the reference count on
+ *
+ * Increments the reference count on a closure to force it staying
+ * alive while the caller holds a pointer to it.
+ *
+ * Returns: The @closure passed in, for convenience
+ */
+EXPORT_C GClosure*
+g_closure_ref (GClosure *closure)
+{
+  guint new_ref_count;
+  g_return_val_if_fail (closure != NULL, NULL);
+  g_return_val_if_fail (closure->ref_count > 0, NULL);
+  g_return_val_if_fail (closure->ref_count < CLOSURE_MAX_REF_COUNT, NULL);
+
+  INC_ASSIGN (closure, ref_count, &new_ref_count);
+  g_return_val_if_fail (new_ref_count > 1, NULL);
+
+  return closure;
+}
+
+/**
+ * g_closure_invalidate:
+ * @closure: GClosure to invalidate
+ *
+ * Sets a flag on the closure to indicate that its calling
+ * environment has become invalid, and thus causes any future
+ * invocations of g_closure_invoke() on this @closure to be
+ * ignored. Also, invalidation notifiers installed on the closure will
+ * be called at this point. Note that unless you are holding a
+ * reference to the closure yourself, the invalidation notifiers may
+ * unref the closure and cause it to be destroyed, so if you need to
+ * access the closure after calling g_closure_invalidate(), make sure
+ * that you've previously called g_closure_ref().
+ *
+ * Note that g_closure_invalidate() will also be called when the
+ * reference count of a closure drops to zero (unless it has already
+ * been invalidated before).
+ */
+EXPORT_C void
+g_closure_invalidate (GClosure *closure)
+{
+  g_return_if_fail (closure != NULL);
+
+  if (!closure->is_invalid)
+    {
+      gboolean was_invalid;
+      g_closure_ref (closure);           /* preserve floating flag */
+      SWAP (closure, is_invalid, TRUE, &was_invalid);
+      /* invalidate only once */
+      if (!was_invalid)
+        closure_invoke_notifiers (closure, INOTIFY);
+      g_closure_unref (closure);
+    }
+}
+
+/**
+ * g_closure_unref:
+ * @closure: #GClosure to decrement the reference count on
+ *
+ * Decrements the reference count of a closure after it was previously
+ * incremented by the same caller. If no other callers are using the
+ * closure, then the closure will be destroyed and freed.
+ */
+EXPORT_C void
+g_closure_unref (GClosure *closure)
+{
+  guint new_ref_count;
+
+  g_return_if_fail (closure != NULL);
+  g_return_if_fail (closure->ref_count > 0);
+
+  if (closure->ref_count == 1)	/* last unref, invalidate first */
+    g_closure_invalidate (closure);
+
+  DEC_ASSIGN (closure, ref_count, &new_ref_count);
+
+  if (new_ref_count == 0)
+    {
+      closure_invoke_notifiers (closure, FNOTIFY);
+      g_free (closure->notifiers);
+      g_free (closure);
+    }
+}
+
+/**
+ * g_closure_sink:
+ * @closure: #GClosure to decrement the initial reference count on, if it's
+ *           still being held
+ *
+ * Takes over the initial ownership of a closure.  Each closure is
+ * initially created in a <firstterm>floating</firstterm> state, which
+ * means that the initial reference count is not owned by any caller.
+ * g_closure_sink() checks to see if the object is still floating, and
+ * if so, unsets the floating state and decreases the reference
+ * count. If the closure is not floating, g_closure_sink() does
+ * nothing. The reason for the existance of the floating state is to
+ * prevent cumbersome code sequences like:
+ * |[
+ * closure = g_cclosure_new (cb_func, cb_data);
+ * g_source_set_closure (source, closure);
+ * g_closure_unref (closure); // XXX GObject doesn't really need this
+ * ]|
+ * Because g_source_set_closure() (and similar functions) take ownership of the
+ * initial reference count, if it is unowned, we instead can write:
+ * |[
+ * g_source_set_closure (source, g_cclosure_new (cb_func, cb_data));
+ * ]|
+ *
+ * Generally, this function is used together with g_closure_ref(). Ane example
+ * of storing a closure for later notification looks like:
+ * |[
+ * static GClosure *notify_closure = NULL;
+ * void
+ * foo_notify_set_closure (GClosure *closure)
+ * {
+ *   if (notify_closure)
+ *     g_closure_unref (notify_closure);
+ *   notify_closure = closure;
+ *   if (notify_closure)
+ *     {
+ *       g_closure_ref (notify_closure);
+ *       g_closure_sink (notify_closure);
+ *     }
+ * }
+ * ]|
+ *
+ * Because g_closure_sink() may decrement the reference count of a closure
+ * (if it hasn't been called on @closure yet) just like g_closure_unref(),
+ * g_closure_ref() should be called prior to this function.
+ */
+EXPORT_C void
+g_closure_sink (GClosure *closure)
+{
+  g_return_if_fail (closure != NULL);
+  g_return_if_fail (closure->ref_count > 0);
+
+  /* floating is basically a kludge to avoid creating closures
+   * with a ref_count of 0. so the intial ref_count a closure has
+   * is unowned. with invoking g_closure_sink() code may
+   * indicate that it takes over that intiial ref_count.
+   */
+  if (closure->floating)
+    {
+      gboolean was_floating;
+      SWAP (closure, floating, FALSE, &was_floating);
+      /* unref floating flag only once */
+      if (was_floating)
+        g_closure_unref (closure);
+    }
+}
+
+/**
+ * g_closure_remove_invalidate_notifier:
+ * @closure: a #GClosure
+ * @notify_data: data which was passed to g_closure_add_invalidate_notifier()
+ *               when registering @notify_func
+ * @notify_func: the callback function to remove
+ *
+ * Removes an invalidation notifier.
+ *
+ * Notice that notifiers are automatically removed after they are run.
+ */
+EXPORT_C void
+g_closure_remove_invalidate_notifier (GClosure      *closure,
+				      gpointer       notify_data,
+				      GClosureNotify notify_func)
+{
+  g_return_if_fail (closure != NULL);
+  g_return_if_fail (notify_func != NULL);
+
+  if (closure->is_invalid && closure->in_inotify && /* account removal of notify_func() while it's called */
+      ((gpointer) closure->marshal) == ((gpointer) notify_func) &&
+      closure->data == notify_data)
+    closure->marshal = NULL;
+  else if (!closure_try_remove_inotify (closure, notify_data, notify_func))
+    g_warning (G_STRLOC ": unable to remove uninstalled invalidation notifier: %p (%p)",
+	       notify_func, notify_data);
+}
+
+/**
+ * g_closure_remove_finalize_notifier:
+ * @closure: a #GClosure
+ * @notify_data: data which was passed to g_closure_add_finalize_notifier()
+ *  when registering @notify_func
+ * @notify_func: the callback function to remove
+ *
+ * Removes a finalization notifier.
+ *
+ * Notice that notifiers are automatically removed after they are run.
+ */
+EXPORT_C void
+g_closure_remove_finalize_notifier (GClosure      *closure,
+				    gpointer       notify_data,
+				    GClosureNotify notify_func)
+{
+  g_return_if_fail (closure != NULL);
+  g_return_if_fail (notify_func != NULL);
+
+  if (closure->is_invalid && !closure->in_inotify && /* account removal of notify_func() while it's called */
+      ((gpointer) closure->marshal) == ((gpointer) notify_func) &&
+      closure->data == notify_data)
+    closure->marshal = NULL;
+  else if (!closure_try_remove_fnotify (closure, notify_data, notify_func))
+    g_warning (G_STRLOC ": unable to remove uninstalled finalization notifier: %p (%p)",
+               notify_func, notify_data);
+}
+
+/**
+ * g_closure_invoke:
+ * @closure: a #GClosure
+ * @return_value: a #GValue to store the return value. May be %NULL if the
+ *                callback of @closure doesn't return a value.
+ * @n_param_values: the length of the @param_values array
+ * @param_values: an array of #GValue<!-- -->s holding the arguments on
+ *                which to invoke the callback of @closure
+ * @invocation_hint: a context-dependent invocation hint
+ *
+ * Invokes the closure, i.e. executes the callback represented by the @closure.
+ */
+EXPORT_C void
+g_closure_invoke (GClosure       *closure,
+		  GValue /*out*/ *return_value,
+		  guint           n_param_values,
+		  const GValue   *param_values,
+		  gpointer        invocation_hint)
+{
+  g_return_if_fail (closure != NULL);
+
+  g_closure_ref (closure);      /* preserve floating flag */
+  if (!closure->is_invalid)
+    {
+      GClosureMarshal marshal;
+      gpointer marshal_data;
+      gboolean in_marshal = closure->in_marshal;
+
+      g_return_if_fail (closure->marshal || closure->meta_marshal);
+
+      SET (closure, in_marshal, TRUE);
+      if (closure->meta_marshal)
+	{
+	  marshal_data = closure->notifiers[0].data;
+	  marshal = (GClosureMarshal) closure->notifiers[0].notify;
+	}
+      else
+	{
+	  marshal_data = NULL;
+	  marshal = closure->marshal;
+	}
+      if (!in_marshal)
+	closure_invoke_notifiers (closure, PRE_NOTIFY);
+      marshal (closure,
+	       return_value,
+	       n_param_values, param_values,
+	       invocation_hint,
+	       marshal_data);
+      if (!in_marshal)
+	closure_invoke_notifiers (closure, POST_NOTIFY);
+      SET (closure, in_marshal, in_marshal);
+    }
+  g_closure_unref (closure);
+}
+
+/**
+ * g_closure_set_marshal:
+ * @closure: a #GClosure
+ * @marshal: a #GClosureMarshal function
+ *
+ * Sets the marshaller of @closure. The <literal>marshal_data</literal>
+ * of @marshal provides a way for a meta marshaller to provide additional
+ * information to the marshaller. (See g_closure_set_meta_marshal().) For
+ * GObject's C predefined marshallers (the g_cclosure_marshal_*()
+ * functions), what it provides is a callback function to use instead of
+ * @closure->callback.
+ */
+EXPORT_C void
+g_closure_set_marshal (GClosure       *closure,
+		       GClosureMarshal marshal)
+{
+  g_return_if_fail (closure != NULL);
+  g_return_if_fail (marshal != NULL);
+
+  if (closure->marshal && closure->marshal != marshal)
+    g_warning ("attempt to override closure->marshal (%p) with new marshal (%p)",
+	       closure->marshal, marshal);
+  else
+    closure->marshal = marshal;
+}
+
+/**
+ * g_cclosure_new:
+ * @callback_func: the function to invoke
+ * @user_data: user data to pass to @callback_func
+ * @destroy_data: destroy notify to be called when @user_data is no longer used
+ *
+ * Creates a new closure which invokes @callback_func with @user_data as
+ * the last parameter.
+ *
+ * Returns: a new #GCClosure
+ */
+EXPORT_C GClosure*
+g_cclosure_new (GCallback      callback_func,
+		gpointer       user_data,
+		GClosureNotify destroy_data)
+{
+  GClosure *closure;
+  
+  g_return_val_if_fail (callback_func != NULL, NULL);
+  
+  closure = g_closure_new_simple (sizeof (GCClosure), user_data);
+  if (destroy_data)
+    g_closure_add_finalize_notifier (closure, user_data, destroy_data);
+  ((GCClosure*) closure)->callback = (gpointer) callback_func;
+  
+  return closure;
+}
+
+/**
+ * g_cclosure_new_swap:
+ * @callback_func: the function to invoke
+ * @user_data: user data to pass to @callback_func
+ * @destroy_data: destroy notify to be called when @user_data is no longer used
+ *
+ * Creates a new closure which invokes @callback_func with @user_data as
+ * the first parameter.
+ *
+ * Returns: a new #GCClosure
+ */
+EXPORT_C GClosure*
+g_cclosure_new_swap (GCallback      callback_func,
+		     gpointer       user_data,
+		     GClosureNotify destroy_data)
+{
+  GClosure *closure;
+  
+  g_return_val_if_fail (callback_func != NULL, NULL);
+  
+  closure = g_closure_new_simple (sizeof (GCClosure), user_data);
+  if (destroy_data)
+    g_closure_add_finalize_notifier (closure, user_data, destroy_data);
+  ((GCClosure*) closure)->callback = (gpointer) callback_func;
+  SET (closure, derivative_flag, TRUE);
+  
+  return closure;
+}
+
+static void
+g_type_class_meta_marshal (GClosure       *closure,
+			   GValue /*out*/ *return_value,
+			   guint           n_param_values,
+			   const GValue   *param_values,
+			   gpointer        invocation_hint,
+			   gpointer        marshal_data)
+{
+  GTypeClass *class;
+  gpointer callback;
+  /* GType itype = (GType) closure->data; */
+  guint offset = GPOINTER_TO_UINT (marshal_data);
+  
+  class = G_TYPE_INSTANCE_GET_CLASS (g_value_peek_pointer (param_values + 0), itype, GTypeClass);
+  callback = G_STRUCT_MEMBER (gpointer, class, offset);
+  if (callback)
+    closure->marshal (closure,
+		      return_value,
+		      n_param_values, param_values,
+		      invocation_hint,
+		      callback);
+}
+
+static void
+g_type_iface_meta_marshal (GClosure       *closure,
+			   GValue /*out*/ *return_value,
+			   guint           n_param_values,
+			   const GValue   *param_values,
+			   gpointer        invocation_hint,
+			   gpointer        marshal_data)
+{
+  GTypeClass *class;
+  gpointer callback;
+  GType itype = (GType) closure->data;
+  guint offset = GPOINTER_TO_UINT (marshal_data);
+  
+  class = G_TYPE_INSTANCE_GET_INTERFACE (g_value_peek_pointer (param_values + 0), itype, GTypeClass);
+  callback = G_STRUCT_MEMBER (gpointer, class, offset);
+  if (callback)
+    closure->marshal (closure,
+		      return_value,
+		      n_param_values, param_values,
+		      invocation_hint,
+		      callback);
+}
+
+/**
+ * g_signal_type_cclosure_new:
+ * @itype: the #GType identifier of an interface or classed type
+ * @struct_offset: the offset of the member function of @itype's class
+ *  structure which is to be invoked by the new closure
+ *
+ * Creates a new closure which invokes the function found at the offset
+ * @struct_offset in the class structure of the interface or classed type
+ * identified by @itype.
+ *
+ * Returns: a new #GCClosure
+ */
+EXPORT_C GClosure*
+g_signal_type_cclosure_new (GType    itype,
+			    guint    struct_offset)
+{
+  GClosure *closure;
+  
+  g_return_val_if_fail (G_TYPE_IS_CLASSED (itype) || G_TYPE_IS_INTERFACE (itype), NULL);
+  g_return_val_if_fail (struct_offset >= sizeof (GTypeClass), NULL);
+  
+  closure = g_closure_new_simple (sizeof (GClosure), (gpointer) itype);
+  if (G_TYPE_IS_INTERFACE (itype))
+    g_closure_set_meta_marshal (closure, GUINT_TO_POINTER (struct_offset), g_type_iface_meta_marshal);
+  else
+    g_closure_set_meta_marshal (closure, GUINT_TO_POINTER (struct_offset), g_type_class_meta_marshal);
+  
+  return closure;
+}
+
+
+/**
+ * g_cclosure_marshal_VOID__VOID:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 1
+ * @param_values: a #GValue array holding only the instance
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__BOOLEAN:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #gboolean parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gboolean arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__CHAR:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #gchar parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gchar arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__UCHAR:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #guchar parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, guchar arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__INT:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #gint parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__UINT:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #guint parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, guint arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__LONG:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #glong parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, glong arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__ULONG:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #gulong parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gulong arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__ENUM:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the enumeration parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal> where the #gint parameter denotes an enumeration type..
+ */
+
+/**
+ * g_cclosure_marshal_VOID__FLAGS:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the flags parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal> where the #gint parameter denotes a flags type.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__FLOAT:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #gfloat parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gfloat arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__DOUBLE:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #gdouble parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gdouble arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__STRING:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #gchar* parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, const gchar *arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__PARAM:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #GParamSpec* parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, GParamSpec *arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__BOXED:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #GBoxed* parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, GBoxed *arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__POINTER:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #gpointer parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, gpointer arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__OBJECT:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding the instance and the #GObject* parameter
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, GOBject *arg1, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_VOID__UINT_POINTER:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: ignored
+ * @n_param_values: 3
+ * @param_values: a #GValue array holding instance, arg1 and arg2
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>void (*callback) (gpointer instance, guint arg1, gpointer arg2, gpointer user_data)</literal>.
+ */
+
+/**
+ * g_cclosure_marshal_BOOLEAN__FLAGS:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: a #GValue which can store the returned #gboolean
+ * @n_param_values: 2
+ * @param_values: a #GValue array holding instance and arg1
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>gboolean (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal> where the #gint parameter
+ * denotes a flags type.
+ */
+
+/**
+ * g_cclosure_marshal_BOOL__FLAGS:
+ *
+ * Another name for g_cclosure_marshal_BOOLEAN__FLAGS().
+ */
+/**
+ * g_cclosure_marshal_STRING__OBJECT_POINTER:
+ * @closure: the #GClosure to which the marshaller belongs
+ * @return_value: a #GValue, which can store the returned string
+ * @n_param_values: 3
+ * @param_values: a #GValue array holding instance, arg1 and arg2
+ * @invocation_hint: the invocation hint given as the last argument
+ *  to g_closure_invoke()
+ * @marshal_data: additional data specified when registering the marshaller
+ *
+ * A marshaller for a #GCClosure with a callback of type
+ * <literal>gchar* (*callback) (gpointer instance, GObject *arg1, gpointer arg2, gpointer user_data)</literal>.
+ */
+
+#define __G_CLOSURE_C__
+#include "gobjectaliasdef.c"