Re: Introduction and Wikipedia and Git Blame

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 16, 2009, 20:05 UTC
Message-ID: <7vpr8nt894.fsf@alter.siamese.dyndns.org>
In-Reply-To: <7v7huvuptn.fsf@alter.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

Show 17 quoted lines

> "jamesmikedupont@googlemail.com" <jamesmikedupont@googlemail.com> writes:
>
>>> You would need to postprocess the computed result (either by diff or
>>> blame) to lay out the final text output in either case anyway, and making
>>> the existing blame engine do the work for you would be a better approach,
>>> I think.
>>
>> Please can you tell me what is the basic algorithm of the blame engine?
>
> I think this is one of the most conprehensive write-up on the algorithm:
>
>   http://thread.gmane.org/gmane.comp.version-control.git/28826/focus=28895
>
> The whole thread (at least what I wrote in it) is worth reading if you
> want to understand what the current code does.  The first message in the
> thread talks about "NEEDSWORK" label on an unimplemented part of the code,
> and says "we could", but these gaps were since filled.

Ah, nevermind. The thread is the definitive description of the blame algorithm, but I agree with Dscho that in this case, you either have to change blame itself to do this "byte-wise" comparison internally between versions, or re-do the blame logic yourself like Dscho suggests. Dscho is right in this case; an unmodifled blame engine, unless you feed a history that is converted to use the byte-per-line format, won't help you at all.

So it would be either between rolling a custom byte-wise blame algorithm yourself and teaching a new byte-wise mode to existing blame engine. Sorry for making the task sound much easier than it would be.