food for thought as noticed by a coworker who has been profiling some hot
code to optimize a library...
If a function does not have a return statement we return None. Ironically
this makes the foo2 function below faster than the bar2 function at least as
measured using bytecode size:
Python 2.6.2 (r262:71600, Jul 24 2009, 17:29:21)
[GCC 4.2.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import dis
>>> def foo(x):
... y = x()
... return y
...
>>> def foo2(x):
... return x()
...
>>> def bar(x):
... y = x()
...
>>> def bar2(x):
... x()
...
>>> dis.dis(foo)
2 0 LOAD_FAST 0 (x)
3 CALL_FUNCTION 0
6 STORE_FAST 1 (y)
3 9 LOAD_FAST 1 (y)
12 RETURN_VALUE
>>> dis.dis(foo2)
2 0 LOAD_FAST 0 (x)
3 CALL_FUNCTION 0
6 RETURN_VALUE
>>> dis.dis(bar)
2 0 LOAD_FAST 0 (x)
3 CALL_FUNCTION 0
6 STORE_FAST 1 (y)
9 LOAD_CONST 0 (None)
12 RETURN_VALUE
>>> dis.dis(bar2)
2 0 LOAD_FAST 0 (x)
3 CALL_FUNCTION 0
6 POP_TOP
7 LOAD_CONST 0 (None)
10 RETURN_VALUE
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