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PEP 614: Remove matmul section and clarify the current restrictions (#1305)

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Brandt Bucher 2020-02-13 11:55:28 -08:00 committed by GitHub
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@ -9,15 +9,16 @@ Type: Standards Track
Content-Type: text/x-rst Content-Type: text/x-rst
Created: 10-Feb-2020 Created: 10-Feb-2020
Python-Version: 3.9 Python-Version: 3.9
Post-History: 10-Feb-2020 Post-History: 11-Feb-2020
Resolution: Resolution:
Abstract Abstract
======== ========
This PEP proposes allowing functions and classes to be decorated with Python currently requires that all decorators consist of a dotted
any valid expression. name, optionally followed by a single call. This PEP proposes removing
these limitations and allowing decorators to be any valid expression.
Motivation Motivation
@ -193,29 +194,6 @@ This new grammar is fully backward-compatible with the existing
grammar. grammar.
Binary Matrix Multiplication
----------------------------
One interesting case is the binary ``@`` operator, which was added to
the language after decorators were first introduced. With the proposed
change to the grammar, the following decorator expression will be
unambiguous legal syntax::
@a @ b
def f():
...
However, this pathological case is unlikely to occur in practice, as
there are no known examples of binary matrix multiplication results
which may used as decorators. Likely the only people who would do this
are those who currently write similarly obfuscated toy code::
@_(a
@b)
def f():
...
How To Teach This How To Teach This
================= =================