Collections of non-arbitrary objects ?

[Steve Holden]

walterbyrd wrote:
> On Jun 26, 8:23 am, Bruno Desthuilliers <bruno.
> 42.desthuilli... at wtf.websiteburo.oops.com> wrote:
>> walterbyrda écrit :
>>
>>>> You do program carefully, don't you ?-)
>>> I try. But things like typos are a normal part a life.
>> So are they in any language. I fail to see much difference here.
>>
> 
> For example: if I mis-type a variable name in C, the program will
> probably not even compile. Whereas, with Python, the program will
> probably run, but may give unexpected results.
> 
> 
>>> Guido
>>> must think python has a lot of room for improvement since he's
>>> completely throwing out backward compatibility with python 3000.
>> Not "completely throwing out". Just allowing *some* major breakages -
>> the kind you usually get with each major release of other languages, but
>> that Python managed to avoid as much as possible so far.
> 
> I don't know, but here is a direct quote from Guido's blog: "Python
> 3.0 will break backwards compatibility. Totally."
> 
By which he means he is not, for this one major release only, committed 
to maintaining backwards compatibility with previous versions (which was 
pretty good, though not perfect).

> http://www.artima.com/weblogs/viewpost.jsp?thread=208549
> 
>>> It seems to me that tuple are essentially immutable lists.
>> They are not (even if you can use them that way too). FWIW and IIRC,
>> this is a FAQ.
> 
> A few posters here have stated that tuples are not just immutable but
> when I compare lists, to tuples, I notice that both are ordered
> collections of arbitrary objects, with the primary difference being
> that list are mutable, and tuples are not. It seems to me that if a
> list were immutable, it would be a tuple. That is the one big
> difference.
> 
> Tuples have been compared to records/structures in other languages.
> But, in general, I can not use a for loop to loop through the fields
> in a record, and I can not sort those fields either.
> 
> 
Think of a tuple as an ordered collection. A given element's ordinal 
position indicates its semantics (meaning, significance), and generally 
it won't make sense to iterate over the elements of a tuple (though 
naturally that doesn't stop people, and neither does the interpreter).

Lists are intended for numbered "sets of things", and when all the 
"things" are of the same or closely-related types it's natural to 
iterate over them.

Those who don't "see the need" for tuples need not use them, and their 
programs probably won't be much worse as a result.

regards
  Steve
-- 
Steve Holden        +1 571 484 6266   +1 800 494 3119
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