Function to create a new class using a base class with substituted global scope

inject.py

import types

def clone(original, **newg):
    return types.FunctionType(original.func_code,
                              dict(original.func_globals, **newg),
                              original.func_name,
                              original.func_defaults,
                              original.func_closure)

def inject(cls, **newg):
    newdict = dict(cls.__dict__)

    for methodname,func in cls.__dict__.items():
        if isinstance(func, types.FunctionType):
            for k in newg:
                if k in func.func_code.co_names:
                    newdict[methodname] = clone(func, **newg)
                    break

    return types.ClassType(cls.__name__, (cls, ), newdict)