\openout

yex.keyword.Openout(stream_id, parser)

Source code in yex/keyword/io.py

@yex.decorator.control()
def Openout(stream_id: int, parser):
    parser.eat_optional_char('=')
    parser.eat_optional_spaces()

    filename = yex.filename.Filename.from_parser(parser,
            default_extension = 'tex')

    class Opener(yex.box.Whatsit):
        def render(self):
            parser.doc[f'_outputs'].open(
                    number = stream_id,
                    filename = filename,
                    )

    result = Opener()

    return result