From: Charles Hixson <charleshixsn@...>
Date: 2005-06-02T06:59:43+09:00
Subject: Re: array of object insert polices

dave wrote:

>hy list,
>
>if i have a class as:
>
>class IntegerArrray < Array 
>end
>
>should i check if user inserts non Integer values ?
>
>if yes how?
>if not why?
>
>tnx.
>  
>
The key question is "What is the purpose of 'IntegerArray'?".

That determines both the answers to how and why.

Frequently I'm satisfied with merely ensuring that any value returned is 
a valid integer.  Sometimes, however, I would want to raise an exception 
if the object being added did not respond to to_i, and at other times I 
would want to insist that it actually BE an Integer (well, either a 
Fixnum or a Bignum).

What is the PURPOSE?  That's your keystone.

If you are writing an IntegerArray in a vacuum, then there is no basis 
for making a decision...but were I to do so, I would insist that every 
argument respond to ".to_i", which I would apply before saving it into 
the array by any means whatsoever.  (And I would consider that a foolish 
exercise.)

That said, I frequently find reasons to create similar entities (though 
never yet an IntegerArray).   Generally the reason is so that I can 
store them in, e.g., a file of fixed length blocks.  (Note that this is 
a reason external to Ruby.)  I can also see doing this so that I could 
more easily handle them in a chunk of c code.  (I'm not sure that this 
is a good reason...I haven't tried this yet.)  But I'm always doing it 
for some defined purpose.   (And I often rethink the approach, and try 
something else.)