Re: git versus CVS (versus bk)

From: Linus Torvalds <torvalds@osdl.org>
Date: Oct 31, 2005, 16:18 UTC
Message-ID: <Pine.LNX.4.64.0510310804400.27915@g5.osdl.org>
In-Reply-To: <Pine.LNX.4.63.0510311111340.2916@wbgn013.biozentrum.uni-wuerzburg.de>

On Mon, 31 Oct 2005, Johannes Schindelin wrote:

Show 6 quoted lines

> 
> How about adding the whole explanation as
> 
> 	git/Documentation/howto/tell-why-cvs-sucks.txt
> 
> (maybe with some more polite name)?

Hey, if somebody else does it, that's fine.

I'm personally _so_ biased against CVS that I'm not neutral. I really hate the thing. I'd much rather use tar-balls and patches than CVS: I think "quilt" ends up being much nicer in many ways than CVS can be.

So feel free to take my explanations and write something up. I just don't want to do it, because I fear I might be unfair to CVS (well.. I'm personally 120% convinced I'm not, but still, there's a lot of people who actually _use_ it, so..).

Show 11 quoted lines

> Also, I´d like to add that CVS branching/merging is no good:
> 
> <tryingtoputonalbertsshoes>
> 
> Sometimes a developer gets an idea, or the need, to implement a certain 
> feature to a piece of free software. Now, this idea might seem good, but 
> it might take a while to
> 
> 	- implement it,
> 	- flesh the bugs out, and
> 	- maybe realize the idea was not all that good.

[ details deleted ]

Yes. I consider this to be part of the centralized/distributed issue, but it's worth talking about. A distributed system automatically implies that you can have "throw-away branches" for testing, and you can combine two or more of these test-branches without ever disturbing (or even _notifying_) the "real development" branch.

In a centralized system, any branches will always be in that central repository, so you can't do throw-away stuff without affecting everybody else. Maybe the actual _code_ won't be in the "real development" branch, but you're writing and affecting the same repository where the development happens.

Again, you could replicate the whole repo, and do things there, but then you can't ever merge again, which in effect makes the small branch a big fork. So in that sense the CVS/SVN mentality basically encourages forking and discourages working together. This is more of the same thing that I alluded to when saying that CVS inevitably leads to "politics" - having a central place means that you have people who fight for control over it, even when they'd otherwise _want_ to cooperate.

With git (or with BK, or any truly decentralized model), you just make your own repo, do your development there, and you never need to ask for permissions from the central repo people. If the development works out, you just ask people to merge back. And if it doesn't, you don't even have to tell people what a total failure you were.

So with the distributed model, you don't have to publicly humiliate yourself when you do something stupid. Similarly, you don't have to publicly prove that you're "good enough" before you can play in the sandbox. In other words, there's no need for politics and egos.

(Now, obviously, when you've actually done the work, if people recognize that you're a mental giant, they'll be more likely to merge with you, and you'll generally have an easier time. So I'm not saying that a distributed model takes away the need for showing how good you are, but it doesn't make that a central pre-conception).

			Linus