Re: [Python-Dev] Grammar change in classdef
Talin wrote: Nick Coghlan wrote: As for the reason: it makes it possible to use the same style for classes without bases as is used for functions without arguments. Prior to this change, there was a sharp break in the class syntax, such that if you got rid of the last base class you had to get rid of the parentheses as well. Is the result a new-style or classic-style class? It would be nice if using the empty parens forced a new-style class... This was considered rejected by Guido as too subtle a distinction. So you still need to set __metaclass__=type (or inherit from such a class) to get a new-style class. Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://www.boredomandlaziness.org ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
[Python-Dev] Grammar change in classdef
I've been porting the grammar for pydev to version 2.5 and I've seen
that you can now declare a class in the format: class B():pass
(without the testlist)
-- from the grammar: classdef: 'class' NAME ['(' [testlist] ')'] ':' suite
I think that this change should be presented at
http://docs.python.org/dev/whatsnew/whatsnew25.html
I'm saying that because I've only stumbled upon it by accident -- and
I wasn't able to find any explanation on the reason or semantics of
the change...
Thanks,
Fabio
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Re: [Python-Dev] Grammar change in classdef
I think that this change should be presented at http://docs.python.org/dev/whatsnew/whatsnew25.html It's already listed there: http://docs.python.org/dev/whatsnew/other-lang.html -- Lawrence http://www.oluyede.org/blog ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Grammar change in classdef
Fabio Zadrozny wrote:
I've been porting the grammar for pydev to version 2.5 and I've seen
that you can now declare a class in the format: class B():pass
(without the testlist)
-- from the grammar: classdef: 'class' NAME ['(' [testlist] ')'] ':' suite
I think that this change should be presented at
http://docs.python.org/dev/whatsnew/whatsnew25.html
I'm saying that because I've only stumbled upon it by accident -- and
I wasn't able to find any explanation on the reason or semantics of
the change...
Lawrence already noted that this is already covered by the What's New document
(semantically, it's identical to omitting the parentheses entirely).
As for the reason: it makes it possible to use the same style for classes
without bases as is used for functions without arguments. Prior to this
change, there was a sharp break in the class syntax, such that if you got rid
of the last base class you had to get rid of the parentheses as well.
Cheers,
Nick.
--
Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia
---
http://www.boredomandlaziness.org
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Re: [Python-Dev] Grammar change in classdef
Nick Coghlan wrote: As for the reason: it makes it possible to use the same style for classes without bases as is used for functions without arguments. Prior to this change, there was a sharp break in the class syntax, such that if you got rid of the last base class you had to get rid of the parentheses as well. Is the result a new-style or classic-style class? It would be nice if using the empty parens forced a new-style class... -- Talin ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Grammar change in classdef
On 9/16/06, Talin [EMAIL PROTECTED] wrote: Nick Coghlan wrote: As for the reason: it makes it possible to use the same style for classes without bases as is used for functions without arguments. Prior to this change, there was a sharp break in the class syntax, such that if you got rid of the last base class you had to get rid of the parentheses as well. Is the result a new-style or classic-style class? It would be nice if using the empty parens forced a new-style class... That was my first thought as well. Unfortunately a quick test shows that class Foo(): creates an old style class instead :( -- Gustavo J. A. M. Carneiro The universe is always one step beyond logic. ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Grammar change in classdef
On 9/16/06, Lawrence Oluyede [EMAIL PROTECTED] wrote: I think that this change should be presented at http://docs.python.org/dev/whatsnew/whatsnew25.html It's already listed there: http://docs.python.org/dev/whatsnew/other-lang.html Thanks... also, I don't know if the empty yield statement is mentioned too (I couldn't find it either). Cheers, Fabio ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Grammar change in classdef
That was my first thought as well. Unfortunately a quick test shows that class Foo(): creates an old style class instead :( I think that's because until it'll be safe to break things we will stick with classic by default... -- Lawrence http://www.oluyede.org/blog ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Grammar change in classdef
Lawrence Oluyede wrote: That was my first thought as well. Unfortunately a quick test shows that class Foo(): creates an old style class instead :( I think that's because until it'll be safe to break things we will stick with classic by default... But in this case nothing will be broken, since the () syntax was formerly not allowed, so it won't appear in any existing code. So it would have been a good opportunity to shift over to increased usage new-style classes without breaking anything. Thus, 'class Foo:' would create a classic class, but 'class Foo():' would create a new-style class. However, once it's released as 2.5 that will no longer be the case, as people might start to use () to indicate a classic class. Oh well. -- Talin ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Grammar change in classdef
Talin wrote: Is the result a new-style or classic-style class? It would be nice if using the empty parens forced a new-style class... No, it wouldn't, IMO. Too subtle a clue. Best to just wait for Py3k when all classes will be new-style. -- Greg ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Grammar change in classdef
On 9/16/06, Talin [EMAIL PROTECTED] wrote: Lawrence Oluyede wrote: That was my first thought as well.Unfortunately a quick test shows that class Foo(): creates an old style class instead :( I think that's because until it'll be safe to break things we will stick with classic by default...But in this case nothing will be broken, since the () syntax wasformerly not allowed, so it won't appear in any existing code. So itwould have been a good opportunity to shift over to increased usage new-style classes without breaking anything.Thus, 'class Foo:' would create a classic class, but 'class Foo():'would create a new-style class.However, once it's released as 2.5 that will no longer be the case, as people might start to use () to indicate a classic class. Oh well.We didn't want there to suddenly be a way to make a new-style class that didn't explicitly subclass 'object'.-Brett ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
