UniquePtr

UniquePtr<T> represents a unique owned reference to an instance of type T. When the UniquePtr goes out of scope, the instance will be deallocated.

UniquePtr is used for types that need memory management, but are not reference-counted (for types that that are reference-counted, RefPtr is used instead). The most common type by far it is used with is GLib::Error, where UniquePtr will automatically call g_error_free when the pointer goes out of scope.

UniquePtr is similar to std::unique_ptr with a custom deleter that calls the appropriate function to properly free the referenced GObject type.

Here’s a typical example of using UniquePtr<GLib::Error> to call a function that can potentially fail:

#include <peel/Gtk/Gtk.h>

using namespace peel;

Gtk::ColorDialog *dialog = /* ... */;
Gio::AsyncResult *res = /* ... */;

UniquePtr<GLib::Error> error;
UniquePtr<Gdk::RGBA> color = dialog->choose_rgba_finish (res, &error);

if (error)
  g_print ("Failed to pick color: %s\n", error->message);

Here, Gtk::ColorDialog::choose_rgba_finish both returns an instance of Gdk::RGBA structure allocated on the heap, and on error, sets an out-parameter describing the error.

There’s also an array variant of UniquePtr, which is described on its own page.