Re: More precise tag following

On Sat, 27 Jan 2007, Jakub Narebski wrote:

This is not a hg-only problem.

This is the SAME and FUNDAMENTAL problem that you have any time you think "file identity" matters.

Yes, it's what makes "blame/annotate" fast. But I have tried, over and over again, to explain why it's fundamentally broken (regardless of any blame thing).

So I will just say once again: don't try to make "blame" faster. You can only do so by introducing MUCH MORE serious problems in other parts.

This was a very early design decision in git. It was discussed within hours of me releasing the first version of git. Yes, "git blame" is relatively slow, and it is very very fundamental. It's fundamental exactly because git avoids the mistake that *everybody* else has done.

The upside? I just sent a patch that should make it possible to do a "cool blame" that doesn't feel slow, and in fact allows some nice eyecandy effects (well, it would allow it, if I just knew tcl/tk or something like that: it needs a canvas to draw the existing file into, and then filling in the incremental data as git-blame finds it).

It's going to be tons more fun to watch than any CVS/SVN annotate has ever been. Trust me. I bet that you'll feel that "git blame" is *too* fast, and you'll want the graphical viewer to have a "slow down" flag, just so that you can appreciate the blame building up!

[ Ok, that may not be true for everybody, but having played with "git 
   blame --incremental" a bit I really think it would be a bit cool to 
   have that "slow down" mode, and start things with a really tiny font 
   so you could see the blame build up over a file!

   I'm not kidding you. Eyecandy! And it literally would need git to slow 
   down to make it more human-friendly! ]

The other upside? EVERYTHING ELSE IS FASTER. And I really mean *everything*. Yes, "git blame" is slower than SVN. It will remain so, unless somebody either overrides my objections, or some alien intelligence comes up with something _really_ clever. But look at it this way: blame may take a few seconds, but that's a big part of why you can do merges of things that have tens of thousands of files in half a second.

Things that you would need to go brew a cup of coffee for in some other environments are basically _instantaneous_.

			Linus