[Tutor] Python vs. Ruby

[Alan Gauld]

> > I've used OO long enough to know there are times
> > when it ain't the best answer...
> 
> When not? 
> Isn't everything in Python an object, to some degree?

Yes, but Python doesn't insist that you use an OO approach 
to the solution - as Ruby and Java do. You can write short 
non OO programs in Ruby because there is an outer implies 
class but once you get to bigger programs it becomes 
difficult to create non OO modules, It's not impossible 
but you have to work harder than in Python.

Many problems are better solved using a functional 
programming approach. Others are more amenable to a 
traditional imperative approach(ie procedural).

This is very true of batch programming where you traverse 
a sequence of data applying some algorithm to each 
item in the file. You can do it with objects but 
usually there is little advantage.

Similarly very short programs rarely need the overhead of 
classes - it just increases the code count for little gain.

Think of code libraries - look at Pythons as an example 
- very few of the utility type libraries use an OO design.
Think of the Unix command line programs, most of them can 
be written far more easily using simple functions than 
by using objects.

[ Also the C++ standard library(the STL) is quite deliberately 
non OO, it uses a functional programming approach. That 
was done deliberately to make it as widely applicable as 
possible. ]

OO really comes into its own where the problem gets bigger, 
there are several instances of the same entities in memory 
at one time, the entities have a lot of similarity etc.

So OO is very powerful and appropriate in many (probably most) 
situations, but it is not the only solution. "When all you 
have is a hammer, every problem looks like a nail" applies 
in computing just as much as anywhere else!

Alan G
Author of the Learn to Program web tutor
http://www.freenetpages.co.uk/hp/alan.gauld