Ordered keyword arguments for subcon naming

[Sark Flynn]

After reading Survey-of-Construct3 I started thinking of a way to provide a better mechanism for naming sub-constructs.

After some tinkering, I came to using ordered-keyword-arguments. While this definitely violates basic Python concepts,

it provides an easy-to-use naming mechanism, only requiring every object created to have a serial number (that only

increases.)

To provide a usable demo, I wrote a wrapper module around construct. Here is a simple example showing a construct struct,

and my new equivalent:

from easy_construct import cs, struct

from construct import *

MyStruct = Struct("MyStruct",

                  Magic("EZConstruct"),

                  UBInt32("variable"),

                  UBInt16("another_var"),

                  Padding(0x4),

                  Bytes("array", 13),

                  Magic("MagicEndsHere"),

                  )

MyEasyStruct = 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 MyEasyStruct.parse(sample_data)

    print MyEasyStruct.parse(sample_data) == MyStruct.parse(sample_data)

The easy_construct module is included in the attached files to keep this post short.

What do you think?

[Arek Bulski]

You should look at 2.8 where / operator is used for naming and all fields are name-less. 

I shall change the ctor of Struct to take both a list and kw members in. Note however that kw is unordered before Python 3.6 or so, which is still in beta.

[Arek Bulski]

Made a feature request for this

https://github.com/construct/construct/issues/176