[Tutor] Feedback on coding style

[Albert-Jan Roskam]

Hi,

Re: coding style, I can *really* recommend the book 'Code Complete' 
(http://cc2e.com/). It doesn't focus on Python specifically, but it's a 
wonderful book. You can find a pdf checklist of the book if you Google a bit.
 Cheers!!
Albert-Jan 


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
All right, but apart from the sanitation, the medicine, education, wine, public 
order, irrigation, roads, a fresh water system, and public health, what have the 
Romans ever done for us?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 




________________________________
From: Dave Angel <davea at ieee.org>
To: howitzer at archlinux.us
Cc: tutor at python.org
Sent: Wed, December 8, 2010 11:01:05 PM
Subject: Re: [Tutor] Feedback on coding style

On 01/-10/-28163 02:59 PM, howitzer at archlinux.us wrote:
> Hi.
> 
> For the past week, I've been following an online Python guide named:
> 'Learn Python the Hard Way'. I'm very happy with it as it gives a lot of
> freedom to explore.
> 
> However, due to this I have no idea if I'm thinking the right way. That's
> why I've attached a script of mine I've been working on all day.
> 
> It works a 100%, but I'm afraid I've made very bad choices concerning
> design and coding style. (If it could've been much simpler, if there are
> glaring mistakes, poor methods, ..)
> 
> Could anyone be so friendly as to offer a bit of feedback, to a newbie?
> 
> PS: The script very simple accepts 2 arguments from the commandline.
>     First arg being the number to which should be counted,
>     second arg being the interval.
> 
> Thank you,
> Adrian

I agree with Hugo, probably on all his points.  But to help you fix it, I think 
I can help you a bit as well.

First is I think you're misunderstanding the purpose of a function.  A function 
should be a self-contained piece of code that gets called, and that returns when 
done.  You're using them mostly as a way to implement what BASIC used to have as 
a GOTO.  For example, when a loop is needed, you do it by calling another 
function which calls the first one.  That is called recursion if it's done on 
purpose, and a bug if it happens by accident.

Second is that you're misusing global variables.  A function needs to be called 
with those values it needs to do its work, and it needs to return the results of 
that work.  Very seldom should those things be globals.

Start with the first function.  You declare it with maxn and incr as parameters, 
and you call it correctly.  But it also uses the globals, rather than using the 
ones passed in.

Then the function ask_change().  You should be passing it the two arguments, and 
getting back modified arguments as return values.  And the function shouldn't 
call the_loop() itself, it should just get the new values.

jibjab_result() is trying to be a loop, by effectively calling itself, through 
choice_result().  If you need a loop, just write one.  And that loop will 
probably be in ask_change(), without needing any other functions inside.

It's good to decompose a problem into functions, but you're not using functions 
in the way they're designed.  For small problems, this can work, but as the 
problems get more complex, you'll be forced to change your habits.

DaveA



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