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From: Philipp Stephani <p.stephani2@gmail.com>
To: npostavs@users.sourceforge.net
Cc: 23486@debbugs.gnu.org
Subject: bug#23486: 25.0.93; Modules: features missing from make_function
Date: Sun, 26 Mar 2017 20:02:08 +0000	[thread overview]
Message-ID: <CAArVCkQBmtpRfp7RfY-rXPUqjMfwhXL2GeYHeJyps9Oyeb51fA@mail.gmail.com> (raw)
In-Reply-To: <87inu21o35.fsf@users.sourceforge.net>

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<npostavs@users.sourceforge.net> schrieb am So., 11. Sep. 2016 um 16:56 Uhr:

> Philipp Stephani <p.stephani2@gmail.com> writes:
>
> > emacs_env::make_function lacks the following features supported by
> > `defun':
> >
> > 1. Functions with both optional and rest arguments.
> > 2. Specification of parameter names.
> > 3. Integration with `help-function-arglist'.
> > 4. Specification of interactive forms.
> > 5. Specification of declare forms.
> > 6. Docstrings containing null or non-Unicode characters.
> >
> > (6) is probably rather unimportant.  (5) is probably not implementable
> > (would require wrapping `defun', not `lambda').  (1)–(4) are more severe
> > and quite limit the usefulness of make_function right now; for a
> > truly generic `defun'-like construct one currently has to eval a `defun'
> > form wrapping another function.
>
> Shouldn't modules be providing a DEFUN-like construct instead?  That is,
> I thought the idea of modules was to enable writing primitive
> subroutines.
>

I don't know what the idea of modules originally was. However, defun and
DEFUN are composite operations: They create a function object (lambda) and
provide an alias for it. Therefore they can't replace the more primitive
operations. The current module interface design chooses to provide the
primitive operation to make a function object and have the caller call
defalias. That's a reasonable choice.


>
> >
> > To solve (1)–(3), I'd propose replacing the "arity" arguments with a
> > true arglist specification.  This could either be at the C level, e.g.
> >
> >     ptrdiff_t num_mandatory_args, char** mandatory_arg_names,
> >     ptrdiff_t num_optional_args, char** optional_arg_names,
> >     char* rest_arg_name
> >
> > or by requiring to pass a Lisp argument list.
> >
> > To solve (4) I'd propose to pass another value for the interactive form,
> > probably as emacs_value* (to support non-interactive functions).
> >
> > As an alternative, if people feel this would require too many
> > parameters, I'd propose reverting the change that adds the documentation
> > string.  A docstring without arglist is not very useful.  We could also
> > remove the arity parameters and have the C function check the arity
> > itself.
>
> I think adding "(fn ARG1 ARG2...)" to the docstring would solve (1)-(3).
>

That doesn't work, because Emacs ignores this syntax when the arguments are
provided explicitly, and since a module function is just a (lambda (&rest
args) ...) under the hood, the arglist is always just (&rest args).


> What's lacking is a way to add this automagically like DEFUN does.  And
> getting the parameters in C variables like DEFUN would also be nice.
>

Maybe, but not for the module interface. The module interface explicitly
only provides basic primitives, without macro magic or high-level
functions. High-level functionality built on top of the primitives is out
of scope.

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  reply	other threads:[~2017-03-26 20:02 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-09 16:37 bug#23486: 25.0.93; Modules: features missing from make_function Philipp Stephani
2016-09-11 14:13 ` Philipp Stephani
2016-09-11 14:57 ` npostavs
2017-03-26 20:02   ` Philipp Stephani [this message]
2017-03-26 20:22     ` npostavs
2017-03-26 20:40       ` Philipp Stephani
2017-03-27  3:57 ` npostavs
2017-07-04 18:20   ` Philipp Stephani
2017-07-05  3:40     ` npostavs
2020-09-05 13:59       ` Lars Ingebrigtsen
2020-09-13  9:44         ` Philipp Stephani
2020-09-13 13:20           ` Lars Ingebrigtsen
2020-09-13 18:50             ` Philipp Stephani
2020-12-07 16:42               ` Lars Ingebrigtsen
2020-12-12 14:31                 ` Philipp Stephani

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