[Linux-Biella] Differenze cvs e svn

[Paolo Ciarrocchi]

On 10/4/07, Paolo Ciarrocchi <paolo.ciarrocchi a gmail.com> wrote:
> On 10/3/07, Emanuele Aina <em a nerd.ocracy.org> wrote:
> > Paolo Ciarrocchi indirizzò:
> > «git-commit -a» dovrebbe essere il default, non il contrario.

Why is "git commit -a" not the default?

Most other version control systems will do a full-tree commit, using
the content of files at commit time, by default.

Git does it differently. By default, git commits the content of the
index, and only this. git commit -a gives roughly the equivalent of
what other systems do. Indeed, there are many concrete reasons why
git's way to manage the index is good (and leads to unique features of
git):

    *

      You can do selected files commit with a fine granularity,
telling git what you want to do little by little (git add file to add
the full content of the file to the index, git add -i or git-gui to
add the content hunk-by-hunk, or even use the hunk splitting feature
of git add -i).
    * This selected files commit can help you to keep an uncommited
modification in your tree for a reasonably long time. For example, you
can increment the version number in the Makefile some time before a
release, and use this as a reminder.
    *

      You can perform several small steps for one commit, checking
what you did with git diff, and validating each small step with git
add or git add -u. Typically, you can apply a broken patch, updating
the index, with git apply --index, and then fix the patch. git diff
--cached will show you your fixes, while git diff HEAD will show you
the combined diff.
    *

      This allows excellent merge conflicts management: git diff
--base, git diff --ours, git diff --theirs.
    *

      This allows git commit --amend to amend only the log message if
the index hasn't been modified in the meantime.

So, while using git commit -a is perfectly fine with the simple cycle
"edit/review/commit", making it the default would make other workflow
less natural.

Indeed, the real reason according to Linus is more philosophical: git
is a content tracker, and a file name has no meaning unless associated
to its content. Therefore, the only sane behavior for git add filename
is to add the content of the file as well as its name to the index.

Ciao,

-- 
Paolo