Return Function description as string?

Question

Is it possible to output the content of a user-defined function as a string (not the enumeration, but just the function call):

Function:

def sum(x,y):
    return x+y

Function content as a string:

"sum(), return x+y"

The inspect function might have worked but it seems to be for just python 2.5 and below?

Answer 1

The inspect module works just fine for retrieving source code, this is not limited to older Python versions.

Provided the source is available (e.g. the function is not defined in C code or the interactive interpreter, or was imported from a module for which only the .pyc bytecode cache is available), then you can use:

import inspect
import re
import textwrap

def function_description(f):
    # remove the `def` statement.
    source = inspect.getsource(f).partition(':')[-1]
    first, _, rest = source.partition('\n')
    if not first.strip():  # only whitespace left, so not a one-liner
        source = rest
    return "{}(), {}".format(
        f.__name__,
        textwrap.dedent(source))

Demo:

>>> print open('demo.py').read()  # show source code
def sum(x, y):
    return x + y

def mean(x, y): return sum(x, y) / 2

def factorial(x):
    product = 1
    for i in xrange(1, x + 1):
        product *= i
    return product

>>> from demo import sum, mean, factorial
>>> print function_description(sum)
sum(), return x + y

>>> print function_description(mean)
mean(), return sum(x, y) / 2

>>> print function_description(factorial)
factorial(), product = 1
for i in xrange(1, x + 1):
    product *= i
return product