bug#37538: [PATCH] Add docstring for `tags-complete-tags-table-file'.

[Hong Xu]

On 10/10/19 12:49 AM, Eli Zaretskii wrote:
> > Cc: larsi@gnus.org, 37538@debbugs.gnu.org
> > From: Hong Xu <hong@topbug.net>
> > Date: Wed, 9 Oct 2019 15:58:46 -0700
> >
> > > I actually don't understand why we would like to send the reader to
> > > the manual, instead of describing the effects of WHAT in the doc
> > > string.  Can we just say it right there?
> >
> > The description was quite long and I don't think it is justifiable to copy so 
> > much text over here to the docstring, plus there are additional reference in 
> > the referred manual section.
>
> If you show me what long description you had in mind, I could try
> saying that more concisely as appropriate for a doc string.

This snippet in Programmed Completion section:

   • A flag specifying the type of completion operation to perform; see
     *note Basic Completion::, for the details of those operations.
     This flag may be one of the following values.

     ‘nil’
          This specifies a ‘try-completion’ operation.  The function
          should return ‘nil’ if there are no matches; it should return
          ‘t’ if the specified string is a unique and exact match; and
          it should return the longest common prefix substring of all
          matches otherwise.

     ‘t’
          This specifies an ‘all-completions’ operation.  The function
          should return a list of all possible completions of the
          specified string.

     [other kinds of values]