Re: Completion script for the ctags program

[Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>]

Jacob, ping?  Is a followup patch in the offing?

As already mentioned, I think some of the review points below are
release blockers.

Daniel


Daniel Shahaf wrote on Wed, Feb 24, 2021 at 14:24:37 +0000:
> Jacob Gelbman wrote on Wed, Feb 24, 2021 at 01:20:24 -0600:
> > #compdef ctags
> 
> apt-file(1) on Debian stable shows a few more names:
> 
> arduino-ctags: /usr/bin/arduino-ctags
> emacs-bin-common: /usr/bin/ctags.emacs
> emacs-bin-common: /usr/bin/etags.emacs
> exuberant-ctags: /usr/bin/ctags-exuberant
> universal-ctags: /usr/bin/ctags-universal
> xemacs21-bin: /usr/bin/etags.xemacs21
> 
> I assume at least some of these should be added to the #compdef line.  Would
> you do the honours?
> 
> >     "--alias-<lang>=[add a pattern detecting a name, can be used as an alt name for lang]:pattern"
> 
> As Oliver said, literal angle brackets in the option name to be
> completed aren't especially helpful.  In fact, I'll go as far as to say
> I don't want users to run into it in released code.  Please change them.
> 
> You can use _call_program with --list-languages to generate the right set of
> option names dynamically.
> 
> > elif [ "$_ctags_type" = "exuberant" ]; then
> >   arguments=(
> >     "-a[append to tags file]"
> >     "-B[use backward searching patterns (?...?)]"
> >     "-e[output tag file for use with emacs]"
> >     "-f[write tags to specified file. - is stdout]:file:_files"
> 
> Is the argument to the -f option allowed to be pasted to it?  If so, s/-f/-f+/.
> 
> Also, s/:file:/:output file:/.  That part of the string is a user-facing
> message, so the extra detail is helpful.
> 
> Also, you can drop the "- is stdout" part.  The descriptions are only
> a summary of the functionality; they aren't meant to be a complete copy of
> the manual.
> 
> >     "-F[use forward searching patterns (/.../)]"
> >     "-h[specify list of file extensions to be treated as include files]:"
> 
> Write something after the colon.
> 
> >     "-I[a list of tokens to be specifically handled is read from either the command line or the specified file]:"
> 
> The thing in brackets doesn't describe the action of the option.  Please edit.
> 
> >     "-L[a list of input file names is read from the specified file. - is stdin]:file:_files"
> 
> Rephrase in the imperative.
> 
> >     "-R[equivalent to --recurse]"
> 
> This is normally rendered as:
> 
>       '(-r --recurse)'{-R,--recurse}'[description]'
> 
> >     "--fields=[include selected extension fields (flags afmikKlnsStz)]:flags"
> 
> Recommend to move the afmikKlnsStz thing to after the colon, so it'll be
> shown at a more appropriate point.  Also, it would be helpful to display
> descriptions to the flags using, e.g., «compset» (for the leading plus
> sign) followed by «_values -s ''».
> 
> >     "--file-scope=[should tags scoped only for a single file be included in output]:bool:(yes no)"
> >     "--filter=[behave as a filter, reading file names from stdin and writing tags to stdout]:bool:(yes no)"
> >     "--filter-terminator=[specify string to print to stdout following the tags for each file parsed when --filter is enabled]:string"
> >     "--format=[force output of specified tag file format]:level"
> >     "--help[help text]"
> 
> "help text" is just a noun phrase.  Please use complete decsriptions.
> 
> Please use exclusions if needed («'(--foo)--bar[baz]'»).
> 
> >     "--language-force=[force all files to be interpreted using specified language]:language:->language"
> >     "--languages=[restrict files scanned to these comma-separated languages]:language:->languages"
> 
> Can't say I'm a fan of having two states that differ by a single letter,
> but so be it.
> 
> >     "--recurse=[recurse]:bool:(yes no)"
> 
> Fix the bracketed description.
> 
> > _arguments $arguments
> 
> Pass any arguments to _arguments that may be needed (for
> instance, -s).
> 
> > if [[ "$state" = language* ]]; then
> >   local -a languages
> >   languages=(`ctags --list-languages | cut -d" " -f1`)
> 
> Use _call_program and $service.
> 
> >   if [ "$state" = "language" ]; then
> >     _wanted languages expl language compadd $languages
> 
> Don't pass unsanitized command output to a builtin.  In this case,
> «compadd -a languages» would do.
> 
> >   elif [ "$state" = "languages" ]; then
> >     _values -s , languages $languages
> 
> Don't pass unsanitized command output to a builtin.  I don't know the
> fix off the top of my head.
> 
> Thanks for the patch, and especially for adding exubertant and BSD ctags
> support!
> 
> Daniel
> 
> 
> > 
> > 
> > 
> > 
> > > On Feb 23, 2021, at 10:45 PM, Jacob Gelbman <gelbman@xxxxxxxxx> wrote:
> > > 
> > > Hey, thanks for looking at the script and adding it to the repo, although I think some of got pasted in wrong. There’s a lot to writing completion functions and I’m still not 100% sure how to do it right.
> > > 
> > >> On Feb 23, 2021, at 3:39 PM, Oliver Kiddle <opk@xxxxxxx> wrote:
> > >> 
> > >> Jacob Gelbman wrote:
> > >>> I wrote a completion script for the ctags program. Someone might be able to use it:
> > >> 
> > >> Which ctags!?
> > > 
> > > I have Universal Ctags 5.9.0
> > > 
> > >> This doesn't match what I have installed on any of my systems. There
> > >> are multiple implementations of ctags, with it often being just a link
> > >> to etags - for which there is a completion albeit not a well maintained
> > >> one. One of the main reasons, a completion doesn't already exist is
> > >> that it would ideally need to detect the variant and at least have sane
> > >> fallbacks for variants that aren't handled. It could be useful to check
> > >> what the existing _etags is handling - that might be the exhuberant or
> > >> emacs variant.
> > >> 
> > > 
> > > I located a few other ctags on my computers, I have BSD ctags that comes by default on the mac. Exuberant Ctags 5.8. and there’s etags that comes with emacs. I can probably add an if statement based on the output of ctags —version, and modify the function from that. If it’s etags, I’ll just:
> > > 
> > > _comps[ctags]=“_etags”; _etags
> > > 
> > > And exit.
> > > 
> > >> In general, please follow the conventions outlined in
> > >> Etc/completion-style-guide in the zsh source distribution. For example,
> > >> completion functions usually use just 2 spaces for indentation.
> > >> 
> > >>> #compdef ctags
> > >>> 
> > >>> local state
> > >> 
> > >> If you use states, you need to also handle the context which means
> > >> either passing -C to _arguments and setting up $curcontext or declaring
> > >> context local and passing it to later functions like _values.
> > > 
> > > The -C argument and the context/curcontext variables are confusing me, a lot.
> > > 
> > >> 
> > >>>   "--alias-<lang>=[add a pattern detecting a name, can be used as an alt name for lang]:pattern" \
> > >>>   "--input-encoding-<lang>=[specify encoding of the <lang> input files]:encoding" \
> > >>>   "--kinddef-<lang>=[define new kind for <lang>]:kind" \
> > >>>   "--kinds-<lang>=[enable/disable tag kinds for <lang>]:kind" \
> > >> 
> > >> These would not complete especially helpfully. I suspect that <lang> there is
> > >> supposed to be substituted.
> > > 
> > > They’d show up in the menu when you press tab, but if I filled in the actual values, the list would be too long.
> > > 
> > >> 
> > >>> if [ "$state" = "language" ]; then
> > >>>   compadd `ctags --list-languages | cut -d" " -f1`
> > >> 
> > >> It would be nicer to use a description by calling for example, _wanted
> > >> here.
> > > 
> > > I can do that.
> > > 
> > >> 
> > >>> elif [ "$state" = "languages" ]; then
> > >>>   _values -s , "languages" `ctags --list-languages | cut -d" " -f1`
> > >>> fi
> > >> 
> > >> I'd probably use _sequence here as it is smaller and simpler. But
> > >> _values is fine if none of the languages contain characters that need
> > >> quoting from it.
> > > 
> > > This too.
> > > 
> > >> 
> > >> The return status from this function will not be correct in all cases.
> > >> This can have effects like approximate completion being activated
> > >> despite matches having been added by earlier completers. Where states
> > >> are needed, you nearly always need to either save the status from
> > >> _arguments, typically via a ret variable or check $compstate[nmatches]
> > >> on exit.
> > >> 
> > >> Oliver
> > > 
> > 
> > 
>