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Re: Working with constansts
From: |
Barry Margolin |
Subject: |
Re: Working with constansts |
Date: |
Wed, 13 May 2009 00:59:58 -0400 |
User-agent: |
MT-NewsWatcher/3.5.3b3 (Intel Mac OS X) |
In article <mailman.7052.1242121473.31690.help-gnu-emacs@gnu.org>,
Nikolaj Schumacher <me@nschum.de> wrote:
> Richard Riley <rileyrgdev@googlemail.com> wrote:
>
> >> Because this would incur overhead on every assignment, as it would have
> >> to check whether the variable being assigned was declared as a constant.
> >> Since this is so rarely the case, this overhead could be seen as mostly
> >> wasted and unnecessary.
> >
> > I don't know enough about Lisp than I can only assume that in this case
> > it can not be detected at compile time IF you compile to byte/p code.
>
> "Thanks" to dynamic scoping it cannot be caught at compile time.
It could at least generate a warning.
> (defconst xxx nil)
>
> (defun change-xxx ()
> (setx xxx t)) ;; const or variable?
>
> (let ((xxx nil))
> (change-xxx))
This should also warn about binding a constant.
--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***
- Re: Working with constansts, (continued)
- Message not available
- Message not available
- Message not available
- Re: Working with constansts, Pascal J. Bourguignon, 2009/05/18
- Re: Working with constansts, Nikolaj Schumacher, 2009/05/18
- Message not available
- Re: Working with constansts, Barry Margolin, 2009/05/10
- Re: Working with constansts, Richard Riley, 2009/05/10
- Re: Working with constansts, Nikolaj Schumacher, 2009/05/12
- Message not available
- Re: Working with constansts, Pascal J. Bourguignon, 2009/05/12
- Message not available
- Re: Working with constansts,
Barry Margolin <=
- Re: Working with constansts, Ralf Wachinger, 2009/05/13
- Re: Working with constansts, Barry Margolin, 2009/05/13
- Re: Working with constansts, Thien-Thi Nguyen, 2009/05/11
- Message not available
- Re: Working with constansts, Barry Margolin, 2009/05/11
Re: Working with constansts, Decebal, 2009/05/11