PEP 3107 and stronger typing (note: probably a newbie question)

[Steve Holden]

Paul Rubin wrote:
> John Nagle <nagle at animats.com> writes:
>>      This has been tried.  Original K&R C had non-enforced static typing.
>> All "struct" pointers were equivalent.  It wasn't pretty.
>>
>>      It takes strict programmer discipline to make non-enforced static
>> typing work.  I've seen it work in an aerospace company, but the Python
>> crowd probably doesn't want that level of engineering discipline.
> 
> I think even enforced static types wouldn't cure what I see as the
> looseness in Python.  There is not enough composability of small
> snippets of code.  For example, the "for" statement clobbers its index
> variable and then leaks it to the outside of the loop.  That may be
> more of a culprit than dynamic types.  Perl and C++ both fix this with
> syntax like
> 
>     for (my $i in ...) ...               (perl)  or
>     for (int i = 0; i < n; i++) ...      (C++, Java)
> 
> making a temporary scope for the index variable.  Python even leaks
> the index variable of list comprehensions (I've mostly stopped using
> them because of this), though that's a recognized wart and is due to
> be fixed.
> 
Wow, you really take non-pollution of the namespace seriously. I agree 
it's a wart, but it's one I have happily worked around since day one.

> Python would be helped a lot by some way to introduce temporary
> scopes.  We had some discussion of this recently, concluding that
> there should be a compiler warning message if a variable in a
> temporary scope shadows one from a surrounding scope.

Yeah, well the approach to scoping could really be improved, but if you 
keep your namespaces small it's not difficult to keep things straight. I 
have always been rather guarded in my approach to accessing non-local 
scopes because the coupling is rather less than obvious, and is subject 
to variation due to non-local changes.

regards
  Steve
-- 
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