What exactly is "pass"? What should it be?

[Thomas Rachel]

Am 18.11.2011 05:34 schrieb Dennis Lee Bieber:
 >> def _pass(*args):
 >>      pass
 >>
 >> def long_running_process(arg1, arg2, arg_etc, report = _pass):
 >>      result1 = do_stuff()
 >>      report(result1)
 >
 > So this is a call to a function that just returns a None, which is
 > dropped by the interpreter...

I'm not sure about this. I think, the call will be executed, but the 
callee will return immediately. It is different from call being dropped.

Another optimized alternative could be to do

def long_running_process(arg1, arg2, arg_etc, report=None):
     result1 = do_stuff()
     if report: report(result1)

but I think that is too low benefit at the cost of too much readability.

Such a function call is

   2           0 LOAD_FAST                0 (a)
               3 POP_JUMP_IF_FALSE       16
               6 LOAD_FAST                0 (a)
               9 CALL_FUNCTION            0
              12 POP_TOP
              13 JUMP_FORWARD             0 (to 16)

   3     >>   16 ...

as opposed to just

   2           0 LOAD_FAST                0 (a)
               3 CALL_FUNCTION            0
               6 POP_TOP

with a call target of

   1           0 LOAD_CONST               0 (None)
               3 RETURN_VALUE

I don't think that a call is sooo expensive that it would make any 
noticeable difference.


Thomas

BTW: Sorry, Dennis, for the private mail - I am incapable to use 
Thunderbird correctly :-(