Name Type Access Description
retval object r/w the value returned by the call to the function, if status is GLib.OnceStatus.READY
status GLib.OnceStatus r/w the status of the GLib.Once


class init_enter (location)
class init_leave (location, result)


class GLib.Once

A GLib.Once struct controls a one-time initialization function. Any one-time initialization function must have its own unique GLib.Once struct.

New in version 2.4.

classmethod init_enter(location)[source]
Parameters:location (object) – location of a static initializable variable containing 0
Returns:True if the initialization section should be entered, False and blocks otherwise
Return type:bool

Function to be called when starting a critical initialization section. The argument location must point to a static 0-initialized variable that will be set to a value other than 0 at the end of the initialization section. In combination with GLib.Once.init_leave() and the unique address value_location, it can be ensured that an initialization section will be executed only once during a program’s life time, and that concurrent threads are blocked until initialization completed. To be used in constructs like this:

static gsize initialization_value = 0;

if (g_once_init_enter (&initialization_value))
    gsize setup_value = 42; // initialization code here

    g_once_init_leave (&initialization_value, setup_value);

// use initialization_value here

New in version 2.14.

classmethod init_leave(location, result)[source]
  • location (object) – location of a static initializable variable containing 0
  • result (int) – new non-0 value for value_location

Counterpart to GLib.Once.init_enter(). Expects a location of a static 0-initialized initialization variable, and an initialization value other than 0. Sets the variable to the initialization value, and releases concurrent threads blocking in GLib.Once.init_enter() on this initialization variable.

New in version 2.14.