Difference between generators and functions returning generators

Question

I was debugging some code with generators and came to this question. Assume I have a generator function

def f(x):
    yield x

and a function returning a generator:

def g(x):
    return f(x)

They surely return the same thing. Can there be any differences when using them interchangeably in Python code? Is there any way to distinguish the two (without inspect)?

Answer 1

They will act the same. And about way to distinguish the two (without inspect). In python? Only inspect:

import inspect

print inspect.isgeneratorfunction(g) --> False
print inspect.isgeneratorfunction(f) --> True

Of course you can also check it using dis:

Python 2.7.6 (default, Jun 22 2015, 17:58:13) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> def f(x):
...     yield x
... 
>>> def g(x):
...     return f(x)
... 
>>> import dis
>>> dis.dis(f)
  2           0 LOAD_FAST                0 (x)
              3 YIELD_VALUE         
              4 POP_TOP             
              5 LOAD_CONST               0 (None)
              8 RETURN_VALUE        
>>> dis.dis(g)
  2           0 LOAD_GLOBAL              0 (f)
              3 LOAD_FAST                0 (x)
              6 CALL_FUNCTION            1
              9 RETURN_VALUE  

but inspect is more appropriate.