From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 14 May 2012 18:13:01 GMT
Subject: Re: [PATCH v5] completion: add new __git_complete helper
Message-ID: <7vmx5ahbrm.fsf@alter.siamese.dyndns.org>
In-Reply-To: <CAMP44s1pb+J_SAzZ66QVcWq4V=LauUQ2VmzMD8KBtnhjubkkVg@mail.gmail.com>

Felipe Contreras <felipe.contreras@gmail.com> writes:

>>> +__git_func_wrap ()
>>> +{
>>> +     if [[ -n ${ZSH_VERSION-} ]]; then
>>> +             emulate -L bash
>>> +             setopt KSH_TYPESET
>>> +
>>> +             # workaround zsh's bug that leaves 'words' as a special
>>> +             # variable in versions < 4.3.12
>>> +             typeset -h words
>>> +
>>> +             # workaround zsh's bug that quotes spaces in the COMPREPLY
>>> +             # array if IFS doesn't contain spaces.
>>> +             typeset -h IFS
>>> +     fi
>>> +     local cur words cword prev
>>> +     _get_comp_words_by_ref -n =: cur words cword prev
>>> +     $1
>>> +}
>>> +
>>> +# Setup completion for certain functions defined above by setting common
>>> +# variables and workarounds.
>>> +# This is NOT a public function; use at your own risk.
>>> +__git_complete ()
>>> +{
>>> +     local wrapper="__git_wrap${2}"
>>> +     eval "$wrapper () { __git_func_wrap $2 ; }"
>>> +     complete -o bashdefault -o default -o nospace -F $wrapper $1 2>/dev/null \
>>> +             || complete -o default -o nospace -F $wrapper $1
>>> +}
>>> +
>>> +__git_complete git _git
>>> +__git_complete gitk _gitk
>>
>> It makes my stomach queasy whenever I see $var not in double quotes that
>> forces me to guess (and trace to verify if the codepath is what I really
>> care about) if any value with $IFS in it could be used there, so even when
>> they are known to be safe, I'd prefer to see either explicit quotes or
>> comment that says what are expected in $1 and $2.
>
> Which ones?

All of them ;-)

Here is my attempt to explain why none of them needs to be quoted:

 # Setup completion for certain functions defined above by setting common
 # variables and workarounds.
 # It takes two parameters:
 #  - the first is the command name on the command line to complete its
 #    arguments for the user;
 #  - the second is a name of the completion function
 # This is NOT a public function; use at your own risk.
 #
 # Note that none of the variable reference in the implementation of this
 # function needs dq around it.
 #
 # wrapper: the name of an internal shell function that wraps the
 #          completion function $2, formed by prefixing "__git_wrap"
 #          in front of it.  As it has to be usable as a name of a
 #          shell function, by definition there won't be $IFS characters
 #          in it.
 # $1:      the command name on the command line---ditto.
 # $2:      the shell function name that implements the completion-ditto.

Once there is such an explanation, the answer to the next question would
become...

>>> +     $1
>>> +     complete -o bashdefault -o default -o nospace -F $wrapper $1 2>/dev/null \
>>> +             || complete -o default -o nospace -F $wrapper $1
>
> So you want:
>
>   "$1"

... Not really.