Re: [Gnu-arch-users] Why we might use subversion instead of arch.

[Miles Bader]

On Fri, Feb 20, 2004 at 12:41:05PM -0700, Pierce T. Wetter III wrote:
>  Arch lets me cache if I understand correctly. My objection is more 
> philosophical:
> 
>   The build source should match some set of files on the repository.
> 
>  (pretend you don't trust patch. In that case, you'd really like a snapshot
> of HEAD to always be stored somewhere...)

Heh, I think you've got this exactly backwards: it's subversion that should
make you very nervous as it stores everything in a giant opaque binary blob;
if something goes wrong, you'd better cross your fingers.

Arch's archive format, by contrast, is very straight-forward and robust: 

 (1) It is basically entirely humanly accessible and even modifiable (with
     appropriate caution), using only common GNU tools (tar, gzip, patch).
     If all copies of tla were to suddenly disappear, you'd really have no
     problem extracting all your data, and you could even continue to
     commit revisions by hand!!!

 (2) Even more importantly, it _never_ changes the files/directories
     corresponding to a revision after it's been committed; _all_
     subsequent changes (new commits, branches, tags, etc) only add new
     files/directories.  This is a very desirable characteristic for
     robustness (and should make your backup program like you a lot :-).

You may not trust patch (well actually it's `diff' that you've got to worry
about, since that's where the archive contents come from), but do you trust
subversion's binary-blob-updater more?  Fundamentally, you've _got_ to
trust something -- after all even `cp' (or the underlying filesystem!) can
screw up your data -- but at least can gain some comfort from your tool
being simple and in widespread use, something which I think can be fairly
said of the low-level utilities that tla uses (diff, tar, etc).

[Note, I've only used subversion briefly, and don't really want to rag on
them, but what I know of their approach makes me _very_ nervous; arch's
simplicity and transparency, by contrast, is very refreshing.]

-miles
-- 
The secret to creativity is knowing how to hide your sources.
  --Albert Einstein