Re: git subtree error (just how do you expect me to merge 0 trees?)

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 1, 2013, 03:16 UTC
Message-ID: <7v7gnxd24h.fsf@alter.siamese.dyndns.org>
In-Reply-To: <87licd3b7w.fsf@waller.obbligato.org>

greened@obbligato.org writes:

> git-subtree add accepts either a refspec or a path to a repository and a
> refspec.

> With one positional option, git-subtree add simply assumes
> it's a refspec.  Is there an easy way to check whether a string is a
> proper refspec?  Even better would be a way to check if a string is a
> path to a git repository.

Do you literally mean "a path to a repository" in the above, or do you mean "a remote that is like what is accepted by 'git fetch'"? If you literary mean it is is a path to a git repository, you could obviously use "cd $there && git rev-parse --git-dir" or something.

On the other hand, if you mean the command takes a remote and an optional list of refspecs just like "git fetch" does, then I am not sure it is a good design in the first place to allow "refspecs only", if only to keep the interface similar to "git fetch" (you cannot omit remote and give refspecs, as you cannot interpret refspecs without knowing in the context of which remote they are to be interpreted).

I would imagine you could disambiguate and default to "origin" or something when you guessed that remote was omitted if you really wanted to, with a syntacitical heuristics, such as "a refspec will never have two colons in it", "a URL tends to begin with a short alphabet word, a colon and double-slash", etc.