Re: defmacro with built-in gensym declaration and initialization

[Basil L. Contovounesios]

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