symbolimpl.py

import sys
import opcode
import struct


OPNAME = struct.Struct('B')
ARG = struct.Struct('H')


class Symbol(object):

    def __init__(self):
        caller_frame = sys._getframe(1)
        ic = caller_frame.f_lasti
        code = caller_frame.f_code.co_code
        names = caller_frame.f_code.co_names

        (op,) = OPNAME.unpack(code[ic])
        assert opcode.opname[op] == 'CALL_FUNCTION'
        ic += (OPNAME.size + ARG.size)

        (op,) = OPNAME.unpack(code[ic])
        if opcode.opname[op] != 'STORE_NAME':
            raise RuntimeError("Must assign symbol a name!")

        ic += OPNAME.size
        (idx,) = ARG.unpack(code[ic:ic + ARG.size])
        self.name = names[idx]

    def __repr__(self):
        return "<Symbol '{}>".format(self.name)


MetaInfo = Symbol()

d = {MetaInfo: 1, 'a': 2}