Language Design: list_for scope?

[guthrie]

Larry Bates wrote:

> First things first:
> 
> Don't name a variable "dict" because if you do it shadows
> the built in dict function (same goes for list, str, ...).
> This WILL bite you later, so start now by not naming
> variables by any built in names.
-- Thanks, got it!
> 
> Now to your question:
> 
> for x in <something>: requires <something> be an iterable
> (e.g. list, tuple, iterable class instance, etc) so there
> is something that it can loop over one object at at time.
> 
> 
>>for x in [ x in dict if dict[x]=="thing" ]:
> 
> 
> needs to be written (if I'm understanding what you are
> doing) as:
> 
> for x in [x for x in d if d[x]=="thing"]:
-- Ywes, I understand the syntax, but think it is repetitive and cumbersome.

Just note the "for x in x for x in ..."
   no new semantics of the desired iteration set given, all redundant 
syntax.

I still wonder why one cannot qualify a for list iteration object with 
an list_if

Greg


>>For example;
>>Instead of;
>>     for x in [ x in dict if dict[x]=="thing" ]:
>>in this:
>>     for x in dict and dict[x]=="thing":
>>x is undefined.
>>
>>And why doesn't this work:
>>    for x in dict if dict[x]=="thing":
>>
>>Any insights/hints on why it is broken?
>>
>>Thanks,
>>Gregory
>>----------------------------------------
>>http://docs.python.org/ref/grammar.txt:
>>list_for ::=
>>             "for" expression_list "in" testlist
>>              [list_iter]
>>testlist ::=
>>             test ( "," test )* [ "," ]
>>list_iter ::=
>>             list_for | list_if
>>list_if ::=
>>             "if" test [list_iter]
>>
>>
>>----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet
>>News==----
>>http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+
>>Newsgroups
>>----= East and West-Coast Server Farms - Total Privacy via Encryption =----


----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----