Compares the user data for the key quark on object with oldval, and if they are the same, replaces oldval with newval.

This is like a typical atomic compare-and-exchange operation, for user data on an object.

If the previous value was replaced then ownership of the old value (oldval) is passed to the caller, including the registered destroy notify for it (passed out in old_destroy). It’s up to the caller to free this as needed, which may or may not include using old_destroy as sometimes replacement should not destroy the object in the normal way.

class ObjectG


quark GQuark

a GQuark, naming the user data pointer

oldval void*

the old value to compare against

newval void*

the new value

destroy GDestroyNotify

a destroy notify for the new value

oldDestroy GDestroyNotify

destroy notify for the existing value

Return Value

Type: bool

TRUE if the existing value for quark was replaced by newval, FALSE otherwise.