From: Daniel Barkalow Date: Mon, 31 Aug 2009 17:06:24 GMT Subject: Re: What's cooking in git.git (Aug 2009, #05; Wed, 26) Message-ID: In-Reply-To: <7vskfat07h.fsf@alter.siamese.dyndns.org> On Sat, 29 Aug 2009, Junio C Hamano wrote: > Daniel Barkalow writes: > > >> There was a discussion that suggests that the use of colon ':' before vcs > >> helper name needs to be corrected. Nothing happened since. > > > > I believe the outcome of that discussion was: > > > > - We want to keep supporting using regular location URLs that are URLs of > > git repositories (e.g., http://git.savannah.gnu.org/cgit/xboard.git), > > and we probably want to do it with a helper which runs when > > run_command() is given "remote-". I think installing hardlinks > > in EXECPATH ended up being the best implementation here. > > That is different from what I recall. > > I think you said in the above to mean that in the general URL > syntax, refers to the token before the colon, and you would be > feeding the rest (i.e. after the colon, and for many 's it > typically begins with //) to the scheme. > > A flaw with this that was pointed out was that this conflicts with the > scp-like syntax. A remote.$name.url of foo:bar/baz could name > $HOME/bar/baz on host foo (perhaps a nickname in .ssh/config), or the > source "foo" helper recognizes with the name bar/baz. > > If I recall correctly, suggestions made later in the discussion were to > use either + or :: as the prefix to avoid this issue, and > use it to choose remote- (and I think I probably would vote for > double-colon, if only to avoid confusion with our own earlier misdesigned > syntax git+ssh://), so the canonical syntax would be: (with the syntax +, "git+ssh://" would specify the helper "git", which is as good an explicit identifier of the internal handling as any) > > :: > > while we would support obvious short-hands for transports we traditionally > supported without explicit "::" prefix when we choose to eject it > from "built-in" set of transports. > > E.g. http://git.savannah.gnu.org/cgit/xboard.git would be handled by curl > based walker, so if you spell it in the very canonical form, the url would > be curl::http://git.savannah.gnu.org/cgit/xboard.git, but nobody has to > use it. Instead, the transport dispatcher internally recognizes http:// > and picks the curl based walker helper, which is remote-curl without any > extra hardlinks. If the policy is that we're going to have "traditionally supported" schemes, where the internal code knows what helper supports them, I can fix up the series so that the curl-based helper is named "curl", and we can say that the check for "http://", "ftp://", and "https://" is recognizing traditionally-supported schemes, and we can defer coming up with what the syntax for the explicit handler selection is. (For that matter, if there's a // after the colon, it's obviously not a handy ssh-style location, since the second slash would do nothing) I think you're right that we decided that things we used to support internally are a special case, and there's no need to try to generalize them to be the general mechanism (even though I think we simultaneously worked out how to implement the design we were abandoning, which confused my memory). > > - We want to support a separate "vcs" option for cases where repositories > > in the foreign system need to be addressed through the combination of a > > bunch of options, which will be read from the configuration by the > > helper. The helper which gets run is "remote-". > > This is in pu. > > After you explained this in the thread (I think for the second time), I > see no problem with this, except that I think to support this we should > notice and raise an error when we see a remote has both vcs and url, > because the only reason we would want to say "vcs", if I recall your > explanation correctly, is that such a transport does not have the concept > of URL, i.e. a well defined single string that identifies the repository. A user who mostly uses Perforce as a foreign repositories but is using a SVN repo on occasion might want to use "vcs" regardless, but I agree with forcing the helper to use a different option for the case of a URL that git isn't going to look at. That is, you ought to be able to use: [remote "origin"] vcs = svn (something) = http://svn.savannah.gnu.org/... But "(something)" shouldn't be "url". So my changes will be: - name the curl-based helper executable "git-remote-curl", and run it for traditionally supported schemes by special-case. - prohibit using both "vcs" and "url" in a remote. Agreed? -Daniel *This .sig left intentionally blank*