Construct Suggestion - Ordered Keyword Arguments

demo.py

from easy_construct import cs, struct, Container

MyStruct = struct("MyStruct",
                  _0=cs.Magic("EZConstruct"),
                  variable=cs.UBInt32,
                  another_var=cs.UBInt16,
                  _1=cs.Padding(0x4),
                  array=cs.Bytes(13),
                  _2=cs.Magic("MagicEndsHere"),
                  )

sample_data = 'EZConstruct\xde\xad\xbe\xef\x137\x00\x00\x00\x00Hello, World!MagicEndsHere'

if __name__ == '__main__':
    print MyStruct.parse(sample_data)

easy_construct.py

import operator

import construct
from construct import this, Container


class ConstructGetter(object):
    def __init__(self):
        self._index = 0

    def __getattr__(self, name):
        cons = getattr(construct, name)
        proxy = ConstructProxy(cons, self._index)
        self._index += 1
        return proxy


class ConstructProxy(object):
    def __init__(self, cons, index):
        self._cons = cons
        self._index = index
        self._args = []
        self._kwargs = {}
        self._value = None

    def __call__(self, *args, **kwargs):
        self._args = args
        self._kwargs = kwargs
        return self

    def is_name_significant(self, name):
        if name:
            return (name[0] != "_") or (not name[1:].isdigit())
        return False

    def get(self, name):
        if self._value is None:
            if self.is_name_significant(name):
                self._value = self._cons(name, *self._args, **self._kwargs)

            else:
                self._value = self._cons(*self._args, **self._kwargs)

        return self._value


    def __cmp__(self, other):
        return cmp(self._index, other._index)


    def __getattr__(self, name):
        return getattr(self.get(None), name)


cs = ConstructGetter()


def subcons(**members):
    members = members.items()
    members = sorted(members, key=operator.itemgetter(1))
    members = [value.get(name) for name, value in members]
    return members


def struct(name, **members):
    return construct.Struct(name, *subcons(**members))