Help documentation for prefix-commands

Help documentation for prefix-commands

[Christopher Genovese]

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I'd like to be able to add function documentation
to a prefix command that was setup by define-prefix-command.
For instance,

    (put 'pfx-cmd 'function-documentation "doc here yada yada...")

but documentation for keymap "functions" gets eaten in
describe-function-1 in help-fns.el.  The documentation
is found as it should be, but then the function help-fns--signature
kills it for no obvious reason.

In particular, help-fns--signature looks like

  (defun help-fns--signature (function doc real-def real-function)
      (unless (keymapp function)
          ...body))

but if that were changed to

  (defun help-fns--signature (function doc real-def real-function)
     (if (keymapp function)
          doc
       ...body))

any non-nil documentation on the prefix command would be
printed in describe-function and nothing else would be perturbed.

The comments in help-fns--signature (and the name) suggest
that this omission was motivated by not needing a function
signature for the prefix command. But if that's the reason, this
would seem to go too far by suppressing all documentation.

Is there a reason not to allow documentation for prefix commands?
Can this simple change be made?

(Running Gnu Emacs 24.4.1 on Mac OS X 10.7.5.)

Thanks, Chris

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Re: Help documentation for prefix-commands

[Stefan Monnier]

>   (defun help-fns--signature (function doc real-def real-function)
>      (if (keymapp function)
>           doc
>        ...body))

Makes sense, indeed, tank you.  Installed into "master",


        Stefan