[Tutor] Anti-Patterns in Python Programming

[Deb Wyatt]

> -----Original Message-----
> From: alan.gauld at btinternet.com
> Sent: Sat, 12 Jul 2014 19:21:59 +0100
> To: tutor at python.org
> Subject: Re: [Tutor] Anti-Patterns in Python Programming
> 
> On 12/07/14 17:43, Deb Wyatt wrote:
>> 
>>>> So much has been invented since my dos programming days and it is
>>>> overwhelming,
>>> 
>>> Actually very little has been *invented* since your DOS days.
>>> Almost everything we do today was already around back then.
>>> 
>> I knew someone was going to say that.
> 
> :-)
> 
> 
>> Maybe it's the jargon that has been invented?
> 
> In some cases yes, but mostly it was there all
> along just hideen in obscurity. For example all the GUI stuff we take
> for granted really came together at Xerox Park in the 1970's but didn't
> become well known till Steve Jobs paid a visit and promptly built the
> Apple Mac (after initially flopping with the Lisa!) around 1984.
> 
>> Some questions I have at the moment:
>> 
>> 1.  What is functional programming?
>> 2.  What is procedural programming?
>> 3.  What are data patterns?
>> 4.  What are regular expression?
> 
> As Mark has said I always go to Wikipedia for these kinds of answers.
> It is a great resource for all things technical. I'll try to give
> the newbies answers too though...
> 
>  > 1.  What is functional programming?
>  > 2.  What is procedural programming?
> 
> These are both programming paradigms.
> 
> Most programmers learn procedural programming first - also known as
> imperative programming. This is where you tell the computer how to solve
> the problem using the familiar sequences, conditionals and loops. You
> then package these constructs into procedures (or functions).
> You have data floating around loose and your procedures operate
> on that data changing its state(values) as it goes along.
> This means that in a procedural program two calls to the same
> function can return different results even if they have the
> same inputs:
> 
>  >>> state = True
>  >>> def f(n):
> ...   global state
> ...   state = not state
> ...   if state and (n % 2):  # n is odd
> ...      return n ** 2
> ...   else: return n
> ...
>  >>> f(3)
> 3
>  >>> f(3)
> 9
> 
> Functional programming is more like pure math. It is built on functions
> that return values and the values should not depend on external state.
> They always return the same result for the same input. Functional
> programming also attempts (with mixed results) to produce programs that
> look more like problem specifications than solution descriptions. So the
> functions often operate on data sets rather than individuial items
> (avoiding loops) and tend to use recursion a lot.
> ( I have a topic on FP in my tutor that explains more and uses
> Python to illustrate...)
> 
> There are also Object Oriented Programming and Logic Programming
> paradigms.
> 
>  > 3.  What are data patterns?
> 
> This is a bit more open ended since there are several possible answers
> depending on context. At one level it can refer to data modelling
> patterns that crop up again and again. For example instead of modelling
> assigned to each, model it as a person and a role. All the people go in
> Person, all the jobs in role. Then you assign one or more roles to each
> person. When a person gets promoted you don't have to move the data
> between tables you just change the relationships slightly. That is one
> common data pattern in the world of modelling. But it depends on the
> context where you came across the term
> 
>  > 4.  What are regular expression?
> 
> A form of text pattern. They are like wildcards for filenames but more
> powerful. They are used for finding substrings in text. I have another
> topic in my tutorial on regular expressions...
> Nowadays most languages support regular expression searches, including
> most SQL dialects on databases.
> 
>> You all take this understanding for granted, but it's not common
>> knowledge for the rest of the world.
> 
> I sympathise.
> One of the primary aims of my tutorial is to take a complete beginner to
> the point where they can understand these more technical tutorials. A
> lot of time has gone into explaining general computing terminology as
> well as showing how to use it. As far as possible every jargon term is
> explained when first introduced.
>
Thank you very much for your answers.  I'll start going through your tutorial.  I can't wait to hear more about the book you mentioned you were working on a week or two ago.

Deb in WA, USA

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