GObject.Object.dup_data

### Method

# GObject Objectdup_data

since: 2.34

#### Declaration [src]

    gpointer
    g_object_dup_data (
      GObject* object,
      const gchar* key,
      GDuplicateFunc dup_func,
      gpointer user_data
    )

#### Description [src]

This is a variant of `g_object_get_data()` which returns a ‘duplicate’ of the value. `dup_func` defines the meaning of ‘duplicate’ in this context, it could e.g. take a reference on a ref-counted object.

If the `key` is not set on the object then `dup_func` will be called with a `NULL` argument.

Note that `dup_func` is called while user data of `object` is locked.

This function can be useful to avoid races when multiple threads are using object data on the same key on the same object.

Available since: 2.34

This method is not directly available to language bindings.

#### Parameters

`key`

  Type: `const gchar*`

  A string, naming the user data pointer.

  The data is owned by the caller of the method.
  The value is a NUL terminated UTF-8 string.

`dup_func`

  Type: `GDuplicateFunc`

  Function to dup the value.

  The argument can be `NULL`.

`user_data`

  Type: `gpointer`

  Passed as user_data to `dup_func`.

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

#### Return value

Type: `gpointer`

The result of calling `dup_func` on the value associated with `key` on `object`, or `NULL` if not set. If `dup_func` is `NULL`, the value is returned unmodified.

The returned data is owned by the instance.
The return value can be `NULL`.