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.. _why-python3:
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
==========================
-
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