GLibclear_pointer

Clears a reference to a variable.

pp must not be NULL.

If the reference is NULL then this function does nothing. Otherwise, the variable is destroyed using destroy and the pointer is set to NULL.

A macro is also included that allows this function to be used without pointer casts. This will mask any warnings about incompatible function types or calling conventions, so you must ensure that your destroy function is compatible with being called as GDestroyNotify using the standard calling convention for the platform that GLib was compiled for; otherwise the program will experience undefined behaviour.

Examples of this kind of undefined behaviour include using many Windows Win32 APIs, as well as many if not all OpenGL and Vulkan calls on 32-bit Windows, which typically use the __stdcall calling convention rather than the __cdecl calling convention.

The affected functions can be used by wrapping them in a GDestroyNotify that is declared with the standard calling convention:

// Wrapper needed to avoid mismatched calling conventions on Windows
static void
destroy_sync (void *sync)
{
  glDeleteSync (sync);
}

// …

g_clear_pointer (&sync, destroy_sync);

Available since: 2.34

This function is not directly available to language bindings.