On Tue, Apr 10, 2018 at 10:28 PM, Florian Gamböck <mail@xxxxxxxx> wrote: > Adding external subcommands to Git is as easy as to put an executable > file git-foo into PATH. Packaging such subcommands for a Linux > distribution can be achieved by unpacking the executable into /usr/bin > of the user's system. Adding system-wide completion scripts for new > subcommands, however, can be a bit tricky. > > Since bash-completion started to use dynamical loading of completion > scripts since v1.90 (preview of v2.0), I believe the main bash-completion repository can be found at: https://github.com/scop/bash-completion.git This repository still contains the branch 'dynamic-loading'; for the record it points to 3b029892f6f9db3b7210a7f66d636be3e5ec5fa2. Two commits on that branch are worth mentioning: 20c05b43 (Load completions in separate files dynamically, get rid of have()., 2011-10-12) 5baebf81 (Add _xfunc for loading and calling functions on demand, use it in apt-get, cvsps, rsync, and sshfs., 2011-10-13) > it is no longer sufficient to > drop a completion script of a subcommand into the standard completions > path, /usr/share/bash-completion/completions, since this script will not > be loaded if called as a git subcommand. > > For example, look at https://bugs.gentoo.org/544722. To give a short > summary: The popular git-flow subcommand provides a completion script, > which gets installed as /usr/share/bash-completion/completions/git-flow. > > If you now type into a Bash shell: > > git flow <TAB> > > You will not get any completions, because bash-completion only loads > completions for git and git has no idea that git-flow is defined in > another file. You have to load this script manually or trigger the > dynamic loader with: > > git-flow <TAB> # Please notice the dash instead of whitespace > > This will not complete anything either, because it only defines a Bash > function, without generating completions. But now the correct completion > script has been loaded and the first command can use the completions. > > So, the goal is now to teach the git completion script to consider the > possibility of external completion scripts for subcommands, but of > course without breaking current workflows. > > I think the easiest method is to use a function that is defined by > bash-completion v2.0+, namely __load_completion. This is wrong, __load_completion() was introduced in cad3abfc (__load_completion: New function, use in _completion_loader and _xfunc, 2015-07-15), and the first release tag containg it is '2.2' from 2016-03-03. The release tags '1.90' and '2.0' are from 2011-11-03 and 2012-06-17, respectively. This leaves a couple of years long hole where completions were already loaded dynamically but there was no __load_completion() function. Would it be possible to use _xfunc() instead to plug that hole? It seems the be tricky, because that function not only sources but also _calls_ the completion function. > It will take care of > loading the correct script if present. Afterwards, the git completion > script behaves as usual. > > This way we can leverage bash-completion's dynamic loading for git > subcommands and make it easier for developers to distribute custom > completion scripts. > > Signed-off-by: Florian Gamböck <mail@xxxxxxxx> > --- > contrib/completion/git-completion.bash | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash > index b09c8a236..09a820990 100644 > --- a/contrib/completion/git-completion.bash > +++ b/contrib/completion/git-completion.bash > @@ -3096,12 +3096,22 @@ __git_main () > fi > > local completion_func="_git_${command//-/_}" > + if ! declare -f $completion_func >/dev/null 2>/dev/null && > + declare -f __load_completion >/dev/null 2>/dev/null > + then > + __load_completion "git-$command" > + fi > declare -f $completion_func >/dev/null 2>/dev/null && $completion_func && return > > local expansion=$(__git_aliased_command "$command") > if [ -n "$expansion" ]; then > words[1]=$expansion > completion_func="_git_${expansion//-/_}" > + if ! declare -f $completion_func >/dev/null 2>/dev/null && > + declare -f __load_completion >/dev/null 2>/dev/null > + then > + __load_completion "git-$expansion" > + fi > declare -f $completion_func >/dev/null 2>/dev/null && $completion_func > fi > } > -- > 2.16.1 >
