From: Stefan Monnier <monnier@iro.umontreal.ca>
To: "Basil L. Contovounesios" <contovob@tcd.ie>
Cc: akater <nuclearspace@gmail.com>, emacs-devel@gnu.org
Subject: Re: defmacro with built-in gensym declaration and initialization
Date: Thu, 21 Jan 2021 16:05:53 -0500 [thread overview]
Message-ID: <jwvim7qxayx.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <875z3qc8ur.fsf@tcd.ie> (Basil L. Contovounesios's message of "Thu, 21 Jan 2021 20:50:52 +0000")
>> 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).
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.
Stefan
next prev parent reply other threads:[~2021-01-21 21:05 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 [this message]
2021-01-21 21:23 ` Basil L. Contovounesios
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