Why is int(50)<str(5) in python 2.x?

Question

In python 3, int(50)<\'2\' causes a TypeError, and well it should. In python 2.x, however, int(50)<\'2\' returns True

Answer 1

As Aaron said. Breaking it up into your points:

1. Because it makes sort do something halfway usable where it otherwise would make no sense at all (mixed lists). It's not a good idea generally, but much in Python is designed for convenience over strictness.
2. Ordered by type name. This means things of the same type group together, where they can be sorted. They should probably be grouped by type class, such as numbers together, but there's no proper type class framework. There may be a few more specific rules in there (probably is one for numeric types), I'd have to check the source.
3. One is string and the other is unicode. They may have a direct comparison operation, however, but it's conceivable a non-comparable type would get grouped between them, causing a mess. I don't know if there's code to avoid this.

So, it doesn't make sense in the general case, but occasionally it's helpful.

from random import shuffle
letters=list('abcdefgh')
ints=range(8)
both=ints+letters
shuffle(ints)
shuffle(letters)
shuffle(both)
print sorted(ints+letters)
print sorted(both)

Both print the ints first, then the letters.

As a rule, you don't want to mix types randomly within a program, and apparently Python 3 prevents it where Python 2 tries to make vague sense where none exists. You could still sort by lambda a,b: cmp(repr(a),repr(b)) (or something better) if you really want to, but it appears the language developers agreed it's impractical default behaviour. I expect it varies which gives the least surprise, but it's a lot harder to detect a problem in the Python 2 sense.