Python 2.x

Python 2.x has two types to store a string:

• str: bytes string procced as character string which is a mistake
• unicode: character string (unicode)

Both classes has same methods and are very similar.

Python 3000

Python 3000 use two very different types:

• bytes: bytes string which can be see as a list of [0..255] integers
• str: character string (unicode), exactly the same type than Python 2.x "unicode"

old str and new bytes

Differences between Python 2.x "str" and Python 3000 "bytes":

• str is immutable, bytes is mutable
• bytes "lacks" many methods: strip, lstrip, rstrip, lower, upper, etc.

choose between bytes and str

When you migration from Python 2.x to Python 3000, you have to ask youself: do I manipulate characters or bytes (integers)? "A" is a character and 65 is an integer. Examples:

• a network socket manipulate bytes
• a text parser manipulates characters (use lower, strip, etc. methods)

open issues

hash(bytes)

bytes is mutable and so it's not hashable. Hacks/Workaorounds:

• use buffer(value)
• use str8(value)

Other solutions:

• create frozenbytes type
• avoid using hash

Hash is used when bytes is a dictionary key.