[Python-checkins] cpython (3.6): Add text about PEP 526 to What's new in 3.6. Ivan L.

[guido.van.rossum]

https://hg.python.org/cpython/rev/f9b22b1bec2d
changeset:   103769:f9b22b1bec2d
branch:      3.6
parent:      103767:12d88d08f191
user:        Guido van Rossum <guido at python.org>
date:        Tue Sep 13 09:26:38 2016 -0700
summary:
  Add text about PEP 526 to What's new in 3.6. Ivan L.

files:
  Doc/whatsnew/3.6.rst |  38 +++++++++++++++++++++++++++++++-
  1 files changed, 37 insertions(+), 1 deletions(-)


diff --git a/Doc/whatsnew/3.6.rst b/Doc/whatsnew/3.6.rst
--- a/Doc/whatsnew/3.6.rst
+++ b/Doc/whatsnew/3.6.rst
@@ -72,7 +72,7 @@
 
 * PEP 515: Underscores in Numeric Literals
 
-* PEP 526: Syntax for Variable Annotations
+* PEP 526: :ref:`Syntax for Variable Annotations <variable-annotations>`
 
 * PEP 525: Asynchronous Generators
 
@@ -277,6 +277,42 @@
 
 See :pep:`498` and the main documentation at :ref:`f-strings`.
 
+
+.. _variable-annotations:
+
+PEP 526: Syntax for variable annotations
+========================================
+
+:pep:`484` introduced standard for type annotations of function parameters,
+a.k.a. type hints. This PEP adds syntax to Python for annotating the
+types of variables including class variables and instance variables::
+
+    primes: List[int] = []
+
+    captain: str  # Note: no initial value!
+
+    class Starship:
+        stats: Dict[str, int] = {}
+
+Just as for function annotations, the Python interpreter does not attach any
+particular meaning to variable annotations and only stores them in a special
+attribute ``__annotations__`` of a class or module.
+In contrast to variable declarations in statically typed languages,
+the goal of annotation syntax is to provide an easy way to specify structured
+type metadata for third party tools and libraries via the abstract syntax tree
+and the ``__annotations__`` attribute.
+
+.. seealso::
+
+   :pep:`526` -- Syntax for variable annotations.
+      PEP written by Ryan Gonzalez, Philip House, Ivan Levkivskyi, Lisa Roach,
+      and Guido van Rossum. Implemented by Ivan Levkivskyi.
+
+   Tools that use or will use the new syntax:
+   `mypy <http://github.com/python/mypy>`_,
+   `pytype <http://github.com/google/pytype>`_, PyCharm, etc.
+
+
 .. _pep-529:
 
 PEP 529: Change Windows filesystem encoding to UTF-8

-- 
Repository URL: https://hg.python.org/cpython