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