### Method

# Gtk MapListModel set_map_func

#### Declaration [src]

    void
    gtk_map_list_model_set_map_func (
      GtkMapListModel* self,
      GtkMapListModelMapFunc map_func,
      gpointer user_data,
      GDestroyNotify user_destroy
    )

#### Description [src]

Sets the function used to map items.

The function will be called whenever an item needs to be mapped and must return the item to use for the given input item.

Note that `GtkMapListModel` may call this function multiple times on the same item, because it may delete items it doesn’t need anymore.

GTK makes no effort to ensure that `map_func` conforms to the item type of `self`. It assumes that the caller knows what they are doing and the map function returns items of the appropriate type.

#### Parameters

`map_func`

  Type: `GtkMapListModelMapFunc`

  Map function.

  The argument can be `NULL`.

`user_data`

  Type: `gpointer`

  User data passed to `map_func`.

  The argument can be `NULL`.
  The data is owned by the caller of the method.

`user_destroy`

  Type: `GDestroyNotify`

  Destroy notifier for `user_data`.