Trait containing manually implemented methods of
Gets the contents of @self stored in @value.
The @value will have been initialized to the
GType the value should be
provided in. This given
GType does not need to be listed in the formats
ContentProviderExt::formats(). However, if the
GType is not supported, this operation can fail and
G_IO_ERROR_NOT_SUPPORTED will be reported.
true if the value was set successfully. Otherwise
@error will be set to describe the failure.
GValue to fill