parsley_config.py

import argparse
import parsley


def make_argparser(reqs):
    argparser = argparse.ArgumentParser()
    for req in reqs:
        argparser.add_argument('--' + req)
    return argparser


providers_g = '''
args_ = -> argparser.parse_known_args()[0]

args :x = args_:a !(getattr(a, x, None)):r ?(r) -> r
kwargs :x = !(kwargs.get(x)):r ?(r) -> r
'''

providers = parsley.makeGrammar(providers_g, {})


configure_g = '''
address = (kwargs('address'):a -> a)
        | (args('host'):h args('port'):p -> (h, int(p)))
'''

configure = parsley.makeGrammar(configure_g, {}, extends=providers)


def test(**kwargs):
    configurer = configure('')
    configurer._grammar.globals.update(kwargs=kwargs,
                                       argparser=make_argparser(['host',
                                                                 'port']))
    print configurer.address()