And as a counterpoint, I've worked with a number of Senior-level programmers more than old enough to be my parents and seen them behave in some of the most god-awful ways. Resume-Driven-Development, Not-Invented-Here syndrome, refusal to write new tests, refusal to maintain existing tests, breaking the build, deploying broken code. All because of the insidious little "because I (don't) want to."

I'm less convinced that age has anything to do with good outcomes these days as is the discipline to do the responsible things, regardless of how little we wish to do those things.

Yeah at any age you can have problematic developers, but in general the problem is just being prejudice towards an age segment. I think that if the person has proven to be competent they should be given the opportunity and at the same time treated accordingly if they behave like the example you gave.

With an older programmer you have "survivorship bias", meaning the incompetent and not useful have left the profession by then.

Yup, they've successfully transitioned into business roles and run the company.

> I'm less convinced that age has anything to do with good outcomes these days as is the discipline to do the responsible things, regardless of how little we wish to do those things.

The age might also act as a filter, since the best developers are often promoted to the management roles in their 40s and 50s, and are no longer writing much code themselves.

In my experience, people who got promoted to being managers were done so mostly because of their extraversion and people skills - and it makes sense, as these traits make managing easier for them. Unfortunately, not all of them were competent technically - in such cases, the smart ones try to heavily leverage the technical chops of their teams, and just focus on purely managerial duties, such as running interference with the rest of the company etc.

Interesting thought, but I know many programmers (ages ranging from 40 to 70) who refuse to go into anything managerial. I suppose love-of-the-game muddies the waters for that kind of filter.

So you’re saying if you see someone over fifty writing code, odds are they’re not very good at it? That’s a nasty prejudice.

I believe there are many great developers who refuse other positions and still code in their 50s, but an average developer in his 30s could be better than an average developer in his 50s, because many successful developers might transition into higher paid leadership roles or start their own companies when they hit 40s. For instance, Joel Spolsky was still writing software in his mid-30s.

Was Joel Spolsky a great programmer when he was coding?

I assume he was better than an average programmer, since he was responsible for designing Excel Basic at Microsoft. I think the very best programmers keep coding in their 40s and 50s, because there is simply nothing they could be better at. It's the "upper-middle class" of programmers, who often transition into new roles at around 40, because they no longer feel the progress in their careers. How many years can one spend being a Senior Engineer at Google?

I know of senior engineers at Google in their late sixties, and I’m sure there are folks in their seventies there. Some of them are top people in their fields. Donald Knuth is 81 (10000 in ternary) and he still codes for research all the time. My understanding is that Spolsky’s job at Microsoft, which was his first job, was to spec out the then nascent macro language for Excel, he wasn’t a programmer himself, perhaps ever professionally. He does have a lot of opinions on what a great programmer should look like, and isn’t too shy to share them.