Git Checkout File Function

This is an alias function to checkout a file or folder from another branch, mostly as a place to document it since I keep forgetting the syntax.

function gitmefile -d "Checkout folder or file from another branch" \
    --argument-names BRANCH PATH_TO_FILE

I originally called PATH_TO_FILE but that of course clobbered the PATH variable and all of a sudden it couldn't find git.

This is the git command, nothing fancy, although trying to read the documentation didn't make it obvious to me that this is what you should do.

git checkout $BRANCH -- $PATH_TO_FILE

The git error message when you pass it an unknown branch is fatal: invalid reference: <branch> which, in context is relatively easy to figure out, but is a little obscure at first glance, so I'll add an extra message in case there is an error.

if test $status -ne 0
    echo "There was a git error using your arguments: branch='$BRANCH' path='$PATH_TO_FILE'."

    string match --regex --quiet "(?<matched>$BRANCH)" (git branch)
    if test -z $matched
        echo "No branch matches '$BRANCH'."
    end
end

The option given to string match tell fish to use regular expressions instead of the default glob-type expressions and to not echo any matches it finds to the screen. The arguments to test don't have long-versions so I'll put them in a table to make it clearer.

• string-match - match substrings — fish-shell 3.6.1 documentation [Internet]. [cited 2023 Jun 5]. Available from: https://fishshell.com/docs/current/cmds/string-match.html
• test - perform tests on files and text — fish-shell 3.6.1 documentation [Internet]. [cited 2023 Jun 7]. Available from: https://fishshell.com/docs/current/cmds/test.html