Modify function in decorator

Question

I was thinking about making a decorator for the purpose of increasing performance. A decorator that modifies the source code of the function it decorates, and returns the modifi

Answer 1

This works:

import inspect, itertools

def decorate(f):
    source = itertools.dropwhile(lambda line: line.startswith('@'), inspect.getsource(f).splitlines())
    exec('\n'.join(source))
    return eval(f.__name__)

@decorate
def test():
    return 1

I think the problem is the inclusion of the decorator in the function source.

# foo.py
import inspect

def decorate(f):
    print inspect.getsource(f)

@decorate
def test():
    return 1

 

>>> import foo
@decorate
def test():
    return 1
>>> # Notice the decorator is included in the source.

exec sees @decorate for a test defined in a string, so it calls decorate recursively, but this time inspect.getsource fails, because it can't find the source of a function defined in a string.