[Python-3000] self-contained exceptions

[Guido van Rossum]

The case for changing 'for' is weakest, for sure. But 'with' is easy
to coerce into the same category as 'import' and 'except' since it
already uses 'as'...

On 1/11/07, Phillip J. Eby <pje at telecommunity.com> wrote:
> At 08:36 AM 1/11/2007 -0800, Guido van Rossum wrote:
> >Let me clarify. I have no desire to prevent tuple assignment in with
> >statements. But I do think that the tuples could be limited to plain
> >names and other tuples (with similar constraints), and those names
> >should all be zapped at the end of the clause, like for except. And we
> >don't even have to add an extra try/finally to do so, since with
> >already *has* a try/finally...
> >
> >I'm also curious to hear what people think of similarly limiting the
> >syntax of the target in all for-loops -- but WITHOUT the zapping of
> >the variable at block end.
> >
> >I think none of these changes would affect reasonably written code;
> >the use cases for using variables that are part of other objects are
> >too obscure to care.
>
> Yes, they're obscure.  But the symmetry with assignment is pleasing,
> nonetheless.  It gives me the sense of a "small" language, i.e., one
> without nine jillion special cases.
>
> I've been having to do some Perl hacking this week, and I'm being quite
> thoroughly reminded of the joys of how few special cases Python has.  :)
>
> By comparison, Perl is nothing but special cases, as I keep discovering
> that some symbol combination I thought would work, either doesn't, or does
> something entirely different depending on context.  I keep resorting to
> using "map" and a few other tricks to find some Python-like uniformity and
> composability.
>
> Don't get me wrong, I'm not saying that limiting the assignment targets of
> "with" and "for" will turn Python into Perl.  I'm just saying that not
> having to create different mental categories for their assignment targets
> is pleasant.  In contrast, the "as" in "except" and "import" seems to
> already be a different mental category that occurs seamlessly, whereas
> "for" and "with" seem to bunch with "assignment" in my mind.
>
> But of course all this could just be the peculiarities of my own
> mind.  We'll see what other people think.
>
>


-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)