[PATCH v3 0/1] completion: dynamic completion loading

In this small patch I want to introduce a way to dynamically load completion scripts for external subcommands.

A few years ago, you would put a completion script (which defines a Bash function _git_foo for a custom git subcommand foo) into /etc/bash_completion.d, or save it somewhere in your $HOME and source it manually in your .bashrc.

Starting with bash-completion v2.0 (or, to be absolutely exact, the preview versions started at v1.90), completion scripts are not sourced at bash startup anymore. Rather, when typing in a command and trigger completion by pressing the TAB key, the new bash-completion's main script looks for a script with the same name as the typed command in the completion directory, sources it, and provides the completions defined in this script.

However, that only works for top level commands. After a completion script has been found, the logic is delegated to this script. This means, that the completion of subcommands must be handled by the corresponding completion script.

As it is now, git is perfectly able to call custom completion functions, iff they are already defined when calling the git completion. With my patch, git uses an already defined loader function of bash-completion (or continues silently if this function is not found), loads an external completion script, and provides its completions.

An example for an external completion script would be /usr/share/bash-completion/completions/git-foo for a git subcommand foo.

Changes since v2:

-   Replaced __load_completion with _completion_loader, which was introduced 
    way before the former and should therefor be available even in older 
    distributions

-   Updated commit message with explanations from Szeder Gábor

Changes since v1 (RFC):

-   Re-arranged if-fi statement to increase readability (suggested by Junio C 
    Hamano)

-   Re-worded commit message to include the exakt version of bashcomp that 
    introduced dynamic loading (suggested by Stefan Beller)

Florian Gamböck (1):
  completion: load completion file for external subcommand

 contrib/completion/git-completion.bash | 10 ++++++++++
 1 file changed, 10 insertions(+)