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Re: flet, cl-flet, cl-letf in 24.3
From: |
Pascal J. Bourguignon |
Subject: |
Re: flet, cl-flet, cl-letf in 24.3 |
Date: |
Sat, 27 Apr 2013 13:46:20 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux) |
ndemmel@gmail.com writes:
> On Monday, April 22, 2013 3:32:05 PM UTC+2, Stefan Monnier wrote:
>> > as reported here [5], this documentation does not really tell me what to do
>>
>> > if I want to keep relying on the dynamic scoping of flet. A brief google
>>
>> > search [6] leads me to believe that
>>
>>
>>
>> > (cl-letf (((symbol-function 'foo) #'(lambda (...) ...))) ...)
>>
>>
>>
>> > is the suggested solution,
>>
>>
>>
>> That's the case.
>
> Thanks!
>
>>
>> > Does that always have dynamic scope?
>>
>> How could it not?
>>
>
> I'm not sure. What makes you say that?
That's because it's not until run-time that the function slot of the
symbol foo is modified. The _expression_ is evaluated at run-time.
Here we have a literal anonymous function, but it could be any
expression returning a function determined at run-time.
Therefore there's absolutely no way the compiler can know what (foo x)
means inside the cl-letf (apart from the fact that it's a function
call).
Also, since (symbol-function 'foo) is a global place, _while_ the cl-letf
is in effect, (foo x) will call your lambda even outside of the lexical
scope of the cl-letf.
> I can see how a lexical binding
> to a generalized place (not a variable) would not neccessarily make
> sense; is that what you mean?
Indeed.
--
__Pascal Bourguignon__ http://www.informatimago.com/
A bad day in () is better than a good day in {}.
- flet, cl-flet, cl-letf in 24.3, ndemmel, 2013/04/21
- RE: flet, cl-flet, cl-letf in 24.3, Drew Adams, 2013/04/21
- Message not available
- Re: flet, cl-flet, cl-letf in 24.3, ndemmel, 2013/04/21
- RE: flet, cl-flet, cl-letf in 24.3, Drew Adams, 2013/04/21
- Re: flet, cl-flet, cl-letf in 24.3, Stefan Monnier, 2013/04/22
- Re: flet, cl-flet, cl-letf in 24.3, Andreas Röhler, 2013/04/22
- Message not available
- Re: flet, cl-flet, cl-letf in 24.3, ndemmel, 2013/04/27
- Re: flet, cl-flet, cl-letf in 24.3,
Pascal J. Bourguignon <=
- Re: flet, cl-flet, cl-letf in 24.3, Stefan Monnier, 2013/04/27