2 ms·

How do you automatically go from sort( ... some elaborate compare function ...) to sort(key=some completely different function). Yes, there's a wrapper, but it

How do you automatically go from sort( ... some elaborate compare function ...) to sort(key=some completely different function). Yes, there's a wrapper, but it makes the code more convoluted instead of transforming it to the key-paradigm. And if you want to sort by several keys, now you will have to call sort several times. How do you automatically infer the intention of somedict.keys()? Is it going to be used as a list or as an iterator? Those are just off the top of my head. I don't remember all the cases where 2to3 tripped over and produced garbage. But there were too many cases to put actual faith in automatic conversion. It might work if your code is kind of new and homogenic. But looking at how much trouble Dropbox had, even with all the tooling and Guidos they could muster, I have the feeling that your positive experience with 2to3 might rather be the exception than the rule for old and big code bases.

StavrosK 7y ago
> How do you automatically go from sort( ... some elaborate compare function ...) to sort(key=some completely different function). Yes, there's a wrapper Yes, there's a wrapper. You use it, add a comment "this is wrapped in the migration to 3" and move on. > How do you automatically infer the intention of somedict.keys()? Is it going to be used as a list or as an iterator? If it's being iterated on first thing, it's an iterator. If list methods are called on to it, it's a list. This just hasn't been a problem for us, sure, it took some looking at, but it wasn't more than 30 seconds per case. > I have the feeling that your positive experience with 2to3 might rather be the exception than the rule for old and big code bases. Maybe so, but the codebase was ten years old and hundreds of thousands of lines.