Gtk.Expression.Watch_User_Data

Description

Destroy

procedure Destroy (Data : in out User_Data_Type)

Parameters

Data

Gtk_Expression_Notify

type Gtk_Expression_Notify is access procedure (User_Data : User_Data_Type);

Callback called by Gtk.Expression.Watch when the expression value changes.

Parameters

User_Data

data passed to Gtk.Expression.Watch

User_Data_Type

type User_Data_Type (<>) is private;

Watch

function Watch
   (Self      : Gtk.Expression.Gtk_Expression;
    This      : System.Address;
    Notify    : Gtk_Expression_Notify;
    User_Data : User_Data_Type)
    return Gtk.Expression_Watch.Gtk_Expression_Watch

Watch the given expression for changes. The Notify function will be called whenever the evaluation of self may have changed. GTK cannot guarantee that the evaluation did indeed change when the Notify gets invoked, but it guarantees the opposite: When it did in fact change, the Notify will be invoked.

Parameters

Self

This

the this argument to watch

Notify

callback to invoke when the expression changes

User_Data

user data to pass to the notify callback

Return Value

The newly installed watch. Note that the only reference held to the watch will be released when the watch is unwatched which can happen automatically, and not just via [methodGtk.ExpressionWatch.unwatch]. You should call [methodGtk.ExpressionWatch.ref] if you want to keep the watch around. Has transfer-ownership='none'.