Python introspection: return function argument as a string?

Question

Here is what I'd like to be able to do

x = 1

f(x+3) # returns 'x+3' (a string)

Is this possible?

(Lisp and C can do this, but f would have to be a macro)

Answer 1

This is possible, despite what others have said. The only way I can think of to do this is to inspect the source code. I cannot recommend doing this in reality. It's a fun little toy, though.

from inspect import currentframe
import linecache
import re

def f(x):

    cf = currentframe()
    calling_line_number = cf.f_back.f_lineno

    calling_line = linecache.getline(__file__, calling_line_number)
    m = re.search(r"^.*?f\((?P<arg>.*?)\).*$", calling_line)
    if m:
        print (m.group("arg"))

x = 1
f(x + 3)

Prints x + 3, which is exactly what was passed to f().