Interestingly enough, you will quickly find that if you are completely and self-deprecatingly truthful about how much you owe other people, the world at large will treat you as though you did every bit of the invention yourself and are just being becomingly modest about your innate genius. We can all see how well this worked for Linus!
(When I gave my talk at the first Perl Conference in August 1997, hacker extraordinaire Larry Wall was in the front row. As I got to the last line above he called out, religious-revival style, ``Tell it, tell it, brother!''. The whole audience laughed, because they knew this had worked for the inventor of Perl, too.)
After a very few weeks of running the project in the same spirit, I began to get similar praise not just from my users but from other people to whom the word leaked out. I stashed away some of that email; I'll look at it again sometime if I ever start wondering whether my life has been worthwhile :-).
But there are two more fundamental, non-political lessons here that are general to all kinds of design.
12. Often, the most striking and innovative solutions come from realizing that your concept of the problem was wrong.
I had been trying to solve the wrong problem by continuing to develop popclient as a combined MTA/MDA with all kinds of funky local delivery modes. Fetchmail's design needed to be rethought from the ground up as a pure MTA, a part of the normal SMTP-speaking Internet mail path.
When you hit a wall in development-when you find yourself hard put to think past the next patch-it's often time to ask not whether you've got the right answer, but whether you're asking the right question. Perhaps the problem needs to be reframed.
Well, I had reframed my problem. Clearly, the right thing to do was (1) hack SMTP forwarding support into the generic driver, (2) make it the default mode, and (3) eventually throw out all the other delivery modes, especially the deliver-to-file and deliver-to-standard-output options.
I hesitated over step 3 for some time, fearing to upset long-time popclient users dependent on the alternate delivery mechanisms. In theory, they could immediately switch to .forward files or their non-sendmail equivalents to get the same effects. In practice the transition might have been messy.
But when I did it, the benefits proved huge. The cruftiest parts of the driver code vanished. Configuration got radically simpler-no more grovelling around for the system MDA and user's mailbox, no more worries about whether the underlying OS supports file locking.
Also, the only way to lose mail vanished. If you specified delivery to a file and the disk got full, your mail got lost. This can't happen with SMTP forwarding because your SMTP listener won't return OK unless the message can be delivered or at least spooled for later delivery.
Also, performance improved (though not so you'd notice it in a single run). Another not insignificant benefit of this change was that the manual page got a lot simpler.
Later, I had to bring delivery via a user-specified local MDA back in order to allow handling of some obscure situations involving dynamic SLIP. But I found a much simpler way to do it.
The moral? Don't hesitate to throw away superannuated features when you can do it without loss of effectiveness. Antoine de Saint-Exup?ry (who was an aviator and aircraft designer when he wasn't authoring classic children's books) said:
13. ``Perfection (in design) is achieved not when there is nothing more to add, but rather when there is nothing more to take away.''
When your code is getting both better and simpler, that is when you know it's right. And in the process, the fetchmail design acquired an identity of its own, different from the ancestral popclient.
It was time for the name change. The new design looked much more like a dual of sendmail than the old popclient had; both are MTAs, but where sendmail pushes then delivers, the new popclient pulls then delivers. So, two months off the blocks, I renamed it fetchmail.
There is a more general lesson in this story about how SMTP delivery came to fetchmail. It is not only debugging that is parallelizable; development and (to a perhaps surprising extent) exploration of design space is, too. When your development mode is rapidly iterative, development and enhancement may become special cases of debugging-fixing `bugs of omission' in the original capabilities or concept of the software.
