On Thu, Nov 17, 2011 at 6:18 PM, John Ladasky <lada...@my-deja.com> wrote: > Hi folks, > > I'm trying to write tidy, modular code which includes a long-running process. > From time to time I MIGHT like to check in on the progress being made by > that long-running process, in various ways. Other times, I'll just want to > let it run. So I have a section of code which, generally, looks like this: > > def _pass(*args): > pass > > def long_running_process(arg1, arg2, arg_etc, report = _pass): > result1 = do_stuff() > report(result1) > result2 = do_some_different_stuff() > report(result2) > result3 = do_even_more_stuff() > report(result3) > return result3 > > This does what I want. When I do not specify a report function, the process > simply runs. Typically, when I do supply a report function, it would print > something to stdout, or draw an update through a GUI. > > But this approach seems a tad cumbersome and unPythonic to me, particularly > the part where I define the function _pass() which accepts an arbitrary > argument list, and does nothing but... pass.
Seems fine to me (good use of the null object pattern), although I might define _pass() to instead take exactly 1 argument, since that's all you ever call report() with in your example. > This has led me to ask the question, what exactly IS pass? I played with the > interpreter a bit. > > IDLE 2.6.6 ==== No Subprocess ==== >>>> pass >>>> pass() > SyntaxError: invalid syntax >>>> type(pass) > SyntaxError: invalid syntax > > So, pass does not appear to be a function, nor even an object. Is it nothing > more than a key word? Correct: http://docs.python.org/reference/simple_stmts.html#pass http://docs.python.org/reference/lexical_analysis.html#keywords Cheers, Chris -- http://mail.python.org/mailman/listinfo/python-list
