How do I get the return value when using Python exec on the code object of a function?

Yes, you need to have the assignment within the exec statement:

>>> def foo():...     return 5...>>> exec("a = foo()")>>> a5

This probably isn't relevant for your case since its being used in controlled testing, but be careful with using exec with user defined input.

A few years later, but the following snippet helped me:

the_code = '''a = 1b = 2return_me = a + b'''loc = {}exec(the_code, globals(), loc)return_workaround = loc['return_me']print(return_workaround)  # 3

exec() doesn't return anything itself, but you can pass a dict which has all the local variables stored in it after execution. By accessing it you have a something like a return.

I hope it helps someone.

While this is the ugliest beast ever seen by mankind, this is how you can do it by using a global variable inside your exec call:

def my_exec(code):    exec('global i; i = %s' % code)    global i    return i

This is misusing global variables to get your data across the border.

>>> my_exec('1 + 2')3

Needless to say that you should never allow any user inputs for the input of this function in there, as it poses an extreme security risk.