Python3.7 - How to get function signature from the bytecode's code object?

Question

I need to find out function signature from bytecode. I am trying to add inspect functionality to disassembly, but get some problem.

Here is the source code to be compiled to bytecode:

>cat ~/tmp/func.py 
x=100
def foo(n):
    m = 10
    return n + m

a=foo(x)
print(a)

Here is my modification of the dis package in Lib/dis.py:

import inspect   **<== my edit**
def _disassemble_recursive(co, *, file=None, depth=None):
    if depth is None or depth > 0:
        if depth is not None:
            depth = depth - 1 
        for x in co.co_consts:
            if hasattr(x, 'co_code'):
                print(file=file)
                print("Disassembly of function ", x.co_name, x)   **<== my edit**
                sig = inspect.signature(x)
                _disassemble_recursive(x, file=file, depth=depth)

After rebuilding Python, I get the following error in running disassembly:

>python3.7 -m dis ~/tmp/func.py

TypeError: <code object foo at 0x7fd594354ac0, file "~/tmp/func.py", line 2> is not a callable object

My immediate question is - how to get a callable from code object?

Maybe I am on the wrong track, the end goal is, I need to hack Python 3.7's disassembler so that I can get the signature of a function.

Appreciate your help.

Answer 1

This is a really bad way to get a code object's signature, but it's pretty cool to try.

Here's what I did:

import inspect
import types

def sig_from_code(code: types.CodeType):
    return inspect.signature(
        types.FunctionType(code, {})
    )

Hope this helps :D