Fwd: [RFC/FR] Should git checkout (-B|-b) branch master...branch work?
Oops, meant for all of you. -- Forwarded message -- From: Martin von Zweigbergk martinv...@gmail.com Date: Fri, Dec 21, 2012 at 8:45 AM Subject: Re: [RFC/FR] Should git checkout (-B|-b) branch master...branch work? To: Junio C Hamano gits...@pobox.com On Fri, Dec 21, 2012 at 7:58 AM, Junio C Hamano gits...@pobox.com wrote: $ git checkout -B branch old fork point Unfortunately, master...branch syntax does not seem to work for specifying the old fork point for this purpose I have personally always found it confusing to use the same syntax for specifying ranges/sets and single revisions. I keep forgetting what git diff A..B does. I know it doesn't do what I expect (i.e. git diff $(git merge-base A B) B), but I don't know what it does (maybe same as git diff A B (?), but that's besides the point). Having worked a bit on rebase, I know that $onto can also take the A...B form. So there is clearly some precedence for the ... syntax to refer to a revision in some contexts. I would have much preferred if it was possible to make the revision parser generally interpret e.g. A.^.B as the merge base of A and B (failing if not exactly one). It seems like something that must have come up before. Is there a particular reason this would not be a good idea? -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Fwd: [RFC/FR] Should git checkout (-B|-b) branch master...branch work?
Martin von Zweigbergk martinv...@gmail.com writes: I keep forgetting what git diff A..B does. diff is always about two endpoints, not the path that connects these two endpoints (aka range), and when you want to diff between two commits, you say diff A B. A..B happens to be accepted as such only by accident (e.g. the old command line parser did not have a reliable way to tell ^A B and A..B apart), not by design. side note: incidentally, now we have rev_cmdline_info support, we could start deprecating diff A..B syntax. The special case git checkout master...branch is not about specifying a range. The command knows it wants a single point (not two endpoints, nor a range), and A...B as a notation to specify a single point is $(merge-base A B). I would have much preferred if it was possible to make the revision parser generally interpret e.g. A.^.B as the merge base of A and B (failing if not exactly one). Actually, in many places where the command line parser knows it wants a single point, and never a range, we should be able to apply the A...B as a notation to specify a single point rule. Of course you could come up with a symbol other than ... for that purpose, and migrate the current git checkout A...B special case to use that other symbol, but that would be more work and also you would need to retrain existing users. -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Fwd: [RFC/FR] Should git checkout (-B|-b) branch master...branch work?
On 12/21/2012 06:12 PM, Junio C Hamano wrote: diff is always about two endpoints, not the path that connects these two endpoints (aka range), and when you want to diff between two commits, you say diff A B. A..B happens to be accepted as such only by accident (e.g. the old command line parser did not have a reliable way to tell ^A B and A..B apart), not by design. side note: incidentally, now we have rev_cmdline_info support, we could start deprecating diff A..B syntax. I often find myself using git diff A..B syntax when using the command line history because the previous command used A..B; e.g., git log A..B git diff A..B It's quick to recall the previous command, edit log - diff, and press enter; having to remove the dots would require a few extra keypresses. Actually, in many places where the command line parser knows it wants a single point, and never a range, we should be able to apply the A...B as a notation to specify a single point rule. Of course you could come up with a symbol other than ... for that purpose, and migrate the current git checkout A...B special case to use that other symbol, but that would be more work and also you would need to retrain existing users. OTOH making A...B sometimes mean a range and sometimes a merge-base (depending on context) adds a confusing non-uniformity, and also has the disadvantage of making merge-base shorthand unavailable in contexts that allow a range. OTOOH git already has so many notations that can be used on the command line; inventing yet another one would make it that much more overwhelming. Michael -- Michael Haggerty mhag...@alum.mit.edu http://softwareswirl.blogspot.com/ -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Fwd: [RFC/FR] Should git checkout (-B|-b) branch master...branch work?
Off topic: I also find it hard to wrap my head around what diffing against a negative revision would mean. Looking at the result of running it, it seems to be the same as diffing against a positive one. That is not an off-topic at all, but is the crux of diff A..B being a hysterical raisins. It is parsed as and converted to diff ^A B by the revision command line parser in setup_revisions(), and the caller *guesses* what the command line originally said by inspecting that there are two revs in rev.pending[] array, the first one is negative and the second one is positive, to infer that the user typed diff A..B and then finally decides to compare A and B. This was done before we introduced rev.cmdline_info to record what was given from the command line to result in the set of commits in rev.pending array. If we were writing git diff UI from scratch today, we wouldn't be looking at rev.pending but would be looking at rev.cmdline_info and we can differenciate between A B, ^A B, and A..B (and reject the latter two as nonsense). -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: Fwd: [RFC/FR] Should git checkout (-B|-b) branch master...branch work?
On 12/21/2012 10:31 PM, Martin von Zweigbergk wrote: On Fri, Dec 21, 2012 at 11:43 AM, Michael Haggerty mhag...@alum.mit.edu wrote: On 12/21/2012 06:12 PM, Junio C Hamano wrote: side note: incidentally, now we have rev_cmdline_info support, we could start deprecating diff A..B syntax. I often find myself using git diff A..B syntax when using the command line history because the previous command used A..B; e.g., git log A..B git diff A..B The problem with this, to me, if it wasn't clear, is that git log A..B shows you is new _since B branched off from A_, while git diff A..B shows you what has changed _between A and B_. You are quite right, of course, though in many useful cases they are the same. But I guess I should just buck myself up for the new orthodoxy :-) Michael -- Michael Haggerty mhag...@alum.mit.edu http://softwareswirl.blogspot.com/ -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
