GIT argument parsing...Parse --o in format-patch

Question

I don't quite manage to figure out gits argv parsing and would need some help on the way.

I want:
git format-patch -o outdir HEAD~

Work exactly the way it does now, setting output_directory to outdir. But I also want
git format-patch -o HEAD~

to set output_directory with a NULL value so that I can assign a default value to it. Is that even possible with the current argv-parsing implementation?

The currect argv parser is using OPTION_CALLBACK so I thought that that callback should be able to determine if there was an outdir supplied or not.

Or is the correct solution to also add a bolean type OPTION_BOOLEAN for -o?

Answer 1

It's possible to have an "optional" argument by using the PARSE_OPT_OPTARG flag. However, it is not backwards compatible from the user's perspective, as they must use the "sticked" form:

git format-patch -ooutdir ...

to specify the argument. Otherwise, it is not clear in:

 git format-patch -o outdir HEAD~

whether "outdir" is the argument to "-o", or if it is simply the next argument.

However, if you are just interested in "turning off" a previously given argument, we usually spell that with the "--no-" prefix to the long option (e.g., "--no-output-directory" in this case).

I'm not clear how that interacts with your example, though. Your example tries to use "-o" to set output_directory to NULL. But it is already NULL if you do not specify any "-o" at all.