The comment I was specifically replying to asserted that "you could easily write Python 3 compatible code", and could have been doing so 10 years ago.
This is simply untrue— there are a dozen small stumbling blocks that mean that writing bilingual code has a real cost. And it's not as easy as just having the right CI setup, especially if it's ten years ago and most of your dependencies haven't migrated.
Ah, I see the confusion. In this case, "easily" is relative. The assertion "you could easily write Python 3 compatible code" was in response to the (implied?) assertion "you can't do anything to migrate unless your dependencies are migrated". Perhaps "simply" would have been a better word choice than "easily". To your point, writing 2-3 compatible code has a real cost, but to the GP's point, it's the obvious solution to the "can't do anything until deps are migrated" problem.
> To your point, writing 2-3 compatible code has a real cost, but to the GP's point, it's the obvious solution to the "can't do anything until deps are migrated" problem
Q: Ten years ago how would you have explained to your manager that you needed your team to start writing 2-3 compatible code, which obviously takes considerably more time and effort than sticking with 2 compatible code?
At this point, all the code I write is 2/3 compatible, and the things that annoy me are all py3 only features. Backwards compatibility stuff is pretty easy. Most of the easy problems are easy, and six has solved all the hard ones for like 7 years.
And I've been writing some of my code 2/3 compatible since 3.4.
This is simply untrue— there are a dozen small stumbling blocks that mean that writing bilingual code has a real cost. And it's not as easy as just having the right CI setup, especially if it's ten years ago and most of your dependencies haven't migrated.