Saturday, November 24, 2012
I have always been a proponent of revision control systems. Over the years I have found I often want to ressurect old code for some reason, and having an RCS not only made it easier to find old stuff, but also to understand what it had been through, something especially helpful if you intend to hack it up.
Back in the late 80's, it was PVCS on DOS and later Windows. PVCS, it turns out, was a proprietary port of the ancient RCS to DOS. Eventually the repository format changed to something more proprietary, and I began developing on more platforms, so I ended up moving most of my old PVCS repositories to RCS.
RCS stayed with me for years and years, through DOS, Windows, OS/2, Linux. VMS had it's own system, CMS, which was actually pretty good so while I believe I ran RCS on VMS a little, it was never bread and butter on that platform. RCS had many, "better" descendants, CVS, SVN, etc., but RCS stuck with me since it did the job and was available on every platform known to man, much like my beloved Emacs.
Somewhere around 2004 I realized that my PIC code really needed to be in a repo, so I reconstructed as best I could the history of my major PIC projects into RCS.
The PIC development platform, MPLAB, underwent many changes over the years, but the change from MPLAB 5 to MPLAB 6 was pretty major, and I wasn't able to reconstruct the links between those lines of development, so I made separate repos for MPLAB 5 development and MPLAB 6, 7 and 8 development which I prefixed with MPLAB_5 and MPLAB_7.
A few years ago I discovered git. git has a few regressions from RCS, but it is so much easier to use that the incentive is to use it more. So all my repos got converted to git.
Unfortunately, at the time, I hadn't yet learned the beauty of branches. Recall that on RCS and it's descendants, branches are a major pain, so it took me some time to warm up to them.
But when I converted my repos to git, the independent repos from RCS got converted to independent repos on git. With the MPLAB 5 vs. 7 stuff, it would have made much more sense to have branches, but I didn't know that at the time.
Circling back to the CW reader, from time to time I get a request for that code, especially since Francesco's original code has apparently disappeared from the web. I recently got a request from a ham in Scotland, and when I grabbed the code for him, I realized I had been sending out the old MPLAB 5 code, which probably made life difficult for folks wanting to use it.
All this came just as I was struggling with getting a dsPIC30F4013 to talk to an MCP23008, and had just had the aha moment that even though this is a hack and of no permanent value, it still makes sense to put it in a repo and commit like a man posessed, so when the change to make B work causes A to quit, I can easily go back and see where I shot myself in the foot.
git is great!
Which brings me back to Elmer 166. It is clear to me that anyone who thinks he can do serious development without git is either brain dead or a masochist. So it looks like something I should cover. On the other hand, it is kind of off topic. And the folks likely to take the course are probably somewhat unlikely to warm up to it, unless I can present it in a really appealing way.
So, more decisions.