From: "Basil L. Contovounesios" <contovob@tcd.ie>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: akater <nuclearspace@gmail.com>, emacs-devel@gnu.org
Subject: Re: defmacro with built-in gensym declaration and initialization
Date: Thu, 21 Jan 2021 21:23:59 +0000 [thread overview]
Message-ID: <87turaasr4.fsf@tcd.ie> (raw)
In-Reply-To: <jwvim7qxayx.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Thu, 21 Jan 2021 16:05:53 -0500")
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>> Sorry, I suspect I misunderstood. What's a native arglist? Doesn't
>>> defmacro already have native support for &optional and &rest keywords?
>> Yes, and that's what I mean by native arglists - the ones possessed by
>> built-in C objects such as subroutines, lambda expressions, compiled
>> code, dynamic module functions, etc. and used by built-in C functions
>> such as funcall.
>> By contrast, cl-defmacro, other CL compatibility definitions, etc. have
>> to parse a plain Elisp arglist for CL-specific features like &aux.
>
> FWIW, `defmacro` is itself a macro, just like `cl-defmacro`, so it
> wouldn't be that terribly hard (the only problem is that it needs to be
> implemented without itself using macros, more or less).
Oh, right.
> For me it's more a question that whatever something like `&gensym` can't
> use values that are computed during the macro expansion, , so
>
> (defmacro M (ARGS &gensym FOO)
> ...)
>
> is equivalent to something like:
>
> (defmacro M (ARGS)
> (with-gensyms (FOO)
> ...))
>
> except:
> - it's a bit more concise
> - it exposes internal implementation details into the arglist, which is
> usually considered as part of the signature.
> - it doesn't cover the cases where you need `with-gensyms` deeper than
> at the toplevel of the macro's body.
>
> I find the added concision doesn't pay for the other two downsides.
Agreed,
--
Basil
prev parent reply other threads:[~2021-01-21 21:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 8:15 defmacro with built-in gensym declaration and initialization akater
2021-01-20 13:46 ` Basil L. Contovounesios
2021-01-20 15:09 ` Stefan Monnier
2021-01-20 16:47 ` Robin Tarsiger
2021-01-20 19:28 ` akater
2021-01-20 20:55 ` Basil L. Contovounesios
2021-01-21 19:34 ` akater
2021-01-21 20:50 ` Stefan Monnier
2021-01-21 20:50 ` Basil L. Contovounesios
2021-01-21 21:05 ` Stefan Monnier
2021-01-21 21:23 ` Basil L. Contovounesios [this message]
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