Why Python 3? — Python-Future documentation

# Why Python 3?

- Python 2.7 is the final Python 2.x release. Python 3.x is the future. The Python ecosystem needs to consolidate. A split or schism between different incompatible versions is not healthy for growing the community.
- Function annotations
- Decimal module 100x faster. As fast as floats.
- Easier to learn. (Less cruft in language and stdlib, more consistency, better docstrings, etc.)
- Much safer handling of unicode text and encodings: fewer bugs.
- More memory efficiency (shared dict keys (PEP 412) and space-efficient Unicode representation (PEP 393))
- Exception chaining

## Why are Unicode strings better on Python 3?

- it is not the default string type (you have to prefix the string with a u to get Unicode);
- it is missing some functionality, e.g. casefold;
- there are two distinct implementations, narrow builds and wide builds;
- wide builds take up to four times more memory per string as needed;
- narrow builds take up to two times more memory per string as needed;
- worse, narrow builds have very naive (possibly even “broken”) handling of code points in the Supplementary Multilingual Planes.

The unicode string type in Python 3 is better because:

- it is the default string type;
- it includes more functionality;
- starting in Python 3.3, it gets rid of the distinction between narrow and wide builds;
- which reduces the memory overhead of strings by up to a factor of four in many cases;
- and fixes the issue of SMP code points.

(quote from a mailing list post by Steve D’Aprano on 2014-01-17).

## New features

### Standard library:

- SSL contexts in http.client

# Non-arguments for Python 3