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Re: Python Iterables struggling using map() built-in

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Chris Angelico wrote:
> > I'm actually glad PEP 479 will break this kind of code. Gives a good
> > excuse for rewriting it to be more readable.

Steven D'Aprano <steve+comp.lang.python@pearwood.info> wrote:
> What kind of code is that? Short, simple, Pythonic and elegant? :-)
> 
> Here's the code again, with indentation fixed:
> 
> 
> def myzip(*args):
>     iters = map(iter, args)
>     while iters:
>         res = [next(i) for i in iters]
>         yield tuple(res)

Ugh.  When I see "while foo", my brain says, "OK, you're about to see a 
loop which is controlled by the value of foo being changed inside the 
loop".  That's not at all what's happening here, so my brain runs into a 
wall.

Next problem, what the heck is "res"?  We're not back in the punch-card 
days.  We don't have to abbreviate variable names to save columns.  
Variable names are supposed to describe what they hold, and thus help 
you understand the code.  I have no idea what "res" is supposed to be.  
Residue?  Result?  Rest_of_items?  Response?  None of these make much 
sense here, so I'm just left befuddled.

> It would be even more beautiful if we get rid of the unnecessary temporary
> variable:
> 
> def myzip(*args):
>     iters = map(iter, args)
>     while iters:
>         yield tuple([next(i) for i in iters])

Well, that's one way to solve the mystery of what "res" means, but it 
doesn't actually make it easier to understand.

> I think this function makes a good test to separate the masters from the
> apprentices.

The goal of good code is NOT to separate the masters from the 
apprentices.  The goal of good code is to be correct and easy to 
understand by the next guy who comes along to maintain it.
 
> If you can read this function and instantly tell how it works, that it is
> bug-free and duplicates the behaviour of the built-in zip(), you're
> probably Raymond Hettinger. If you can tell what it does but you have to
> think about it for a minute or two before you understand why it works, you
> can call yourself a Python master. If you have to sit down with the
> interactive interpreter and experiment for a bit to understand it, you're
> doing pretty well.

That pretty much is the point I'm trying to make.  If the code is so 
complicated that masters can only understand it after a couple of 
minutes of thought, and those of us who are just "doing pretty well" 
need to sit down and puzzle it out in the REPL, then it's too 
complicated for most people to understand.  KISS beats elegant.

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Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 05:29 +1100
  Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-08 10:33 +1100
    Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 10:50 +1100
      Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-07 19:27 -0500
        Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 11:35 +1100
          Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve@pearwood.info> - 2014-12-08 09:40 +0000
            Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 20:50 +1100
            Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-08 19:02 -0500
    Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-07 19:12 -0500
      Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 11:34 +1100
        Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-07 19:45 -0500
          Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 12:00 +1100
          Re: Python Iterables struggling using map() built-in MRAB <python@mrabarnett.plus.com> - 2014-12-08 03:09 +0000
      Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-07 19:38 -0500
        Re: Python Iterables struggling using map() built-in Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-12-08 18:06 +1300
      Re: Python Iterables struggling using map() built-in Ned Batchelder <ned@nedbatchelder.com> - 2014-12-07 20:06 -0500
      Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-09 13:50 +1100
        Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-09 00:03 -0500
          Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve@pearwood.info> - 2014-12-09 06:40 +0000
        Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-09 15:06 -0500
          Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-10 11:10 +1100
            Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-10 11:20 +1100
            Re: Python Iterables struggling using map() built-in Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-12-10 00:24 +0000
            Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-09 21:44 -0500
              Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve@pearwood.info> - 2014-12-10 09:24 +0000
                Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-10 20:32 +1100
                Re: Python Iterables struggling using map() built-in Marko Rauhamaa <marko@pacujo.net> - 2014-12-10 12:58 +0200
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-10 09:46 -0700
                Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve@pearwood.info> - 2014-12-11 04:01 +0000
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-11 15:00 -0700
                Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-12 10:28 +1100
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-11 16:57 -0700
                Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-11 20:55 -0500
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-12 00:36 -0700
                Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-12 11:44 +1100
                Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-10 12:48 -0500
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-10 13:32 -0700
                Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-10 23:17 -0500
    Re: Python Iterables struggling using map() built-in Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-12-08 18:00 +1300

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