fold

Folds func over the elements of iter.

That is to say, func will be called as func (object, ret, user_data) for each object in this. The normal use of this procedure is to accumulate the results of operating on the objects in ret.

This procedure can be used (and is used internally) to implement the @foreach and find_custom operations.

The fold will proceed as long as func returns true. When the iterator has no more arguments, gst_iterator_done will be returned. If func returns false, the fold will stop, and gst_iterator_ok will be returned. Errors or resyncs will cause fold to return gst_iterator_error or gst_iterator_resync as appropriate.

The iterator will not be freed.

Parameters:

this	The Iterator to fold over
func	the fold function
ret	the seed value passed to the fold function
user_data	user data passed to the fold function

Returns:

A IteratorResult, as described above. MT safe.