a valid gobject.ParamSpec
souce gobject.Value
destination gobject.Value of correct type for pspec
TRUE requires dest_value to conform to pspec without modifications
TRUE if transformation and validation were successful, FALSE otherwise and dest_value is left untouched.
Transforms src_value into dest_value if possible, and then validates dest_value, in order for it to conform to pspec. If strict_validation is TRUE this function will only succeed if the transformed dest_value complied to pspec without modifications.
See also Value.typeTransformable, Value.transform and g_param_value_validate().