karl3＠writeme.com wrote:
This snippet appears to duplicate a code object in the online python interpreter i tried:
import types, inspect f = some_function code_copy = types.CodeType(*[getattr(f.__code__, 'co_'+p.replace('string','').replace('ant','')) for p in inspect.signature(types.CodeType).parameters])
it looks like the CodeType parameters might change across python versions or might not not sure two of them don't match the property names, 'co_code' matches with 'codestring' and 'co_consts' matches with 'constants'. so the two .replace calls perform that matching in a hacky 1-liner
to follow up here, it turns out you can call f.__code__.replace(x=y) to construct code objects with individual properties replaced in python. it returns a new mutated code object. i didn't yet make a sugar library to wrap this, unsure if i will, but here's a rough handcopy of the two functions i wrote. the current issue is that in pdb if the code is restarted the changes have already been applied, so i thought i might add an object that tracks if they have been. def hotpatch_const(f, old, new): 'Mutate a constant in a foreign function.' warnings.warn('Make sure you\'ve submitted an issue or patch to the developers of ' + str(f) + '!') consts = list(f.__code__.co_consts) const_idx = consts.index(old) try: consts.index(old, const_idx + 1) raise ValueError('constant multiply present') except ValueError: pass consts[const_idx] = new f.__code__ = f.__code__.replace(co_consts = tuple(consts)) return f def hotpatch_global(f, name, new): 'Mutate a global in a foreign function.' warnings.warn('Make sure you\'ve submitted an issue or patch to the developers of ' + str(f) + '!') f.__globals__[name] = new return f