[Scummvm-devel] Subversion is here!

Max Horn max at quendi.de
Fri Jan 13 00:39:07 CET 2006


Am 13.01.2006 um 03:09 schrieb Jonathan Gray:

> On Fri, Jan 13, 2006 at 12:28:51AM +1100, ?ystein Eftevaag wrote:
>> Internally, subversion is CVS "done right" and is far more extensible
>> and flexible than CVS.
>>
>> Practical reasons though:
>> * Subversion is a lot faster
>
> Where is this compared?  Also know that GNU CVS has lots of things
> in it that limit speed that are not problems with CVS as such but
> the specific implementation.

Subversion is faster because e.g. a lot of things happen locally, and  
not file-by-file (as CVS does it) but for whole dirs at once.. Think  
about "cvs diff", for example.


>> * Subversion actually makes deleting files, directories, and moving
>> stuff around, trivial.
>> Compared to CVS where it's... not.

To get a bit deeper into it:
* you can *delete* files and directories. Yay, we would have needed  
this a lot
* you can *rename* files! Yay, we would have needed that a lot
* you can *rename* directories, and they have a version, too.
* you can do almost everything you can do in CVS; those things you  
can't do, you usually can't do for *very good reasons*
* branching / tagging is as simple as a copy/move operation. Yay, no  
need for me to re-explain every time how the cryptic branch feature  
of CVS works.
* diffing branches / tags becomes trivial. Yay, no need to specify  
complicated tag/branch statments to CVS where you have to lookup the  
details everytime. No you just specifiy directories
* svn merge helps a lot in merging changes between branches
* yay, file properties are versioned, too. No "executable bit set, go  
modify the repository manually to change it" mess anymore!
* yay, atomic commits. No more partially check in because of Ctrl-C  
during a lengthy commit!
* yay, binary diff's, too! Binary files are first class citizens!


>>
>> The structure of Subversion is also purely directory based, and does
>> away with
>> the branches and modules of CVS. This makes some things more  
>> difficult,
>> but a lot more intuitive and easy to manage.
>
> The size of the source tree is doubled because it keeps copies.

Yeah. This makes a lot of things a lot faster. They figured (IMO  
correctly) that for most people today, hard disk space is no issue,  
but band width *is* an issue. Certainly true for me, I must say :-).  
A clear argument *for* Subversion, I'd say :-)


> diff does not seem to take arguments.

Wrong, ise "svn --help diff" to see that you need -x / --extension to  
pass arbitrary options to diff; in fact you can use --diff-cmd to use  
*any* diff command of your choice! The old "pass any argument I don't  
know to diff" hack was really a bad thing, I am glad they fixed this  
misfeature.


> Keyword expansion seemingly has to be set on a per file basis,
> with no recursive options with no default keywords.

Wrong: <http://svnbook.red-bean.com/en/1.0/ch07s02.html#svn-ch-7- 
sect-2.4>


> man page might as well not exist it is so useless.

It doesn't contain much information, true, but... did you *read*  
it? :-) It points to
* svn help
* in particular: "svn help diff" would have answered your other question
* <http://svnbook.red-bean.com/>
* <http://subversion.tigris.org/>

The latter has e.g. a FAQ <http://subversion.tigris.org/faq.html>  
which would have clarified your statement about keywords, BTW:  
<http://subversion.tigris.org/faq.html#auto-props>



> Many of the people responsible for the security problems in the GNU
> implementation of CVS seem to have moved to working on subversion...

Err... some of the people who made CVS happen in the first place  
moved to Subversion, aye. So what? The design of Subversion is  
*excellent*, while CVS never was designed but grew out of a set of  
hacks atop RCS. It's silly to blame them for security problems (which  
certainly exist) in a product which is currently used way beyond it's  
original purpose.

And anyway, the fundamental security problems are one of the various  
reasons why they wrote Subversion -- to make it right this time :-).

I realize that you are dead set against Subversion at this point (and  
I expected at least one, more likely 2-3 people to react like that),  
but *please* let's keep out the silly GNU vs. BSD discussion line.  
What you call "GNU CVS" is simply "CVS" :-)

Currently tons of people are working on CVS replacements, and I  
really hope we will see CVS be phased out for good in the next couple  
years, in favor of any of Subversion, Monotone, Arch, darcs, etc..  
Don't get me wrong, using CVS beats not using any version control by  
far, but Subversion beats it by equally much in my eyes :-)


Bye,
Max





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