DrProject

I got a fairly significant patch to DrProject today. I wanted to show it to the other developers so they could give it a look over. How'd I do it?

    $ patch -p0 < patch
    ... check that it works ...
    # Create a new branch for the patch
    $ svk cp //drp/trunk //drp/branches/patch -m "Created branch for patch"
    # Do an in-place switch of my repository (which takes about 2 seconds,
    # versus the minute or two it would take to check the entire tree out)
    $ svk switch //drp/branches/patch 
    # Because switch doesn't revert modified files, the changes are still here,
    # ready to be checked in
    $ svk ci -m "Checking in patched code"

Now they can use DrProject's fancy online changeset viewer, checkout the code for themselves, use svn diff... The list is endless.

Now that rocks SO much more than mailing around .diff files (and makes life happier when it comes time to pull it back into trunk).

If there is one thing that I've found universally confusing about version control systems, it's how to revert back to a previous revision, then move on from there. Conventional wisdom would dictate that svn up -r $OLD with some additional flag that says pretend that we're still at HEAD would do the trick... But, alas, there exists no such flag.

So, besides svn cat -r $OLD $FILE > $FILE, what's the best way to revert a file (or entire tree) to an older revision? Well, it turns out that merge is the tool you're looking for.

The trick is that you can diff backwards as well as forwards:

[wolever@thebes] ~/test_dr/All svn diff -r 2:1
Index: stuff
===================================================================
--- stuff       (revision 2)
+++ stuff       (revision 1)
@@ -1,4 +1,3 @@
 Let us endeavor so to live that when we come to die even the undertaker will be
 sorry.
                -- Mark Twain, "Pudd'nhead Wilson's Calendar"
-Increased knowledge will help you now.  Have mate's phone bugged.
Index: docs.html

Which means that merge will work both ways as well:

[wolever@thebes] ~/test_dr/All svn merge -r 2:1 stuff
U    stuff
[wolever@thebes] ~/test_dr/All svn ci -m "reverted changes" stuff
[wolever@thebes] ~/test_dr/All svn diff -r 1:3 stuff
[wolever@thebes] ~/test_dr/All

Of course, this will also work with the myriad of other version control tools out there. In fact, if you're still using SVN, reverting old changes is probably the least of your problems... At least compared to, say, merging different branches ^_^

But that's a post for another day -- I need to stop writing about merging and actually get on with, err, doing it...

After being frustrated with boring white-on-almost-black (spectro) while working with DrProject wiki files, I broke down and wrote a Vim plugin to make the syntax pretty. It will also parse most of the Trac syntax (and more should be easy to add).

Get it: http://wolever.net/~wolever/drpwiki.vim

Using it:

1. Save it to ~/.vim/syntax/drpwiki.vim (create the directory if it doesn't exist)
2. In Vim, enter `:set filetype=drpwiki`