Re: [PATCH v3 3/3] sparse-checkout: limit tab completion to a single level

Lessley Dennington [off-list ref] writes:

quoted

+     # Find possible directory completions, adding trailing '/' characters
+     _tmp_completions="$(git ls-tree -d --name-only HEAD $_tmp_dir |
+         sed -e s%$%/%)"
+

I am admittedly unfamiliar with the use of this format in sed expressions
(I'm generally more accustomed to '/' instead of '%'). It's definitely
working as it should, I'm just not quite sure of how.

The substitution operator "s" in "sed" can take any letter as the
match-replacement delimiter.  People use 's/match/replacement/'
usually because that is how textbooks teach them, but whatever
letter chosen as the delimiter, if it appears in either match or
replacement, it needs to be quoted, i.e. 's/match/replace\/ment/'.

Using a delimiter letter other than '/' relieves you from having to
quote a slash when slash is part of match-replacement.  Even though
it is more common to use a letter that is a more clearly delimiter
looking, e.g. "s|match|replace/ment|", it is not a crime to use
letters like '%' and '#', or even 's' ;-)

quoted

+     if [[ -n "$_tmp_completions" ]]; then
+         # There were some directory completions, so find ones that
+         # start with "$cur", the current token, and put those in COMPREPLY
+         local i=0 c IFS=$' \t\n'

Does c need to be declared before the loop?

quoted

+         for c in $_tmp_completions; do

bash completion script runs in the same namespace as the end-user's
interactive session, so we MUST be careful not to contaminate the
namespace or clobber variable the end-user is using.  "local c" before
we use $c for our own use is a way to make sure that when this function
that says "local c" is left, the value (or non-presence) of "c" is
restored to its original value before this function was entered.