Is using readlines in Python bad code?

Question

I got downvoted for an answer using file.readlines. The critic said that using readlines is crap code (along with other very rude statements).

Is it so bad?

Answer 1

I assume that the problem was the fact that readlines() loads the whole file into memory, which - theoretically - can be a lot.

A lazy approach (iterating over the file and reading progressively as needed) is indeed better in terms of memory usage. Not sure about efficiency, though.

Answer 2

No, readlines is fine. You just have to remember, that the whole file is stored in memory at one point.