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bpo-28638: Optimize namedtuple() creation time by minimizing use of exec() (#3454)

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* Working draft without _source

* Re-use itemgetter() instances

* Speed-up calls to __new__() with a pre-bound tuple.__new__()

* Add note regarding string interning

* Remove unnecessary create function wrappers

* Minor sync-ups with PR-2736.  Mostly formatting and f-strings

* Bring-in qualname/__module fix-ups from PR-2736

* Formally remove the verbose flag and _source attribute

* Restore a test of potentially problematic field names

* Restore kwonly_args test but without the verbose option

* Adopt Inada's idea to reuse the docstrings for the itemgetters

* Neaten-up a bit

* Add news blurb

* Serhiy pointed-out the need for interning

* Jelle noticed as missing f on an f-string

* Add whatsnew entry for feature removal

* Accede to request for dict literals instead keyword arguments

* Leave the method.__module__ attribute pointing the actual location of the code

* Improve variable names and add a micro-optimization for an non-public helper function

* Simplify by in-lining reuse_itemgetter()

* Arrange steps in more logical order

* Save docstring in local cache instead of interning
This commit is contained in:
Raymond Hettinger 2017-09-10 10:23:36 -07:00 • committed by GitHub
parent 3cedf46cdb
commit 8b57d73639
5 changed files with 135 additions and 112 deletions
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18
Doc/library/collections.rst
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@ -763,7 +763,7 @@ Named tuples assign meaning to each position in a tuple and allow for more reada
self-documenting code. They can be used wherever regular tuples are used, and
they add the ability to access fields by name instead of position index.
.. function:: namedtuple(typename, field_names, *, verbose=False, rename=False, module=None)
.. function:: namedtuple(typename, field_names, *, rename=False, module=None)
Returns a new tuple subclass named *typename*. The new subclass is used to
create tuple-like objects that have fields accessible by attribute lookup as
@ -786,10 +786,6 @@ they add the ability to access fields by name instead of position index.
converted to ``['abc', '_1', 'ghi', '_3']``, eliminating the keyword
``def`` and the duplicate fieldname ``abc``.
If *verbose* is true, the class definition is printed after it is
built. This option is outdated; instead, it is simpler to print the
:attr:`_source` attribute.
If *module* is defined, the ``__module__`` attribute of the named tuple is
set to that value.
@ -806,6 +802,9 @@ they add the ability to access fields by name instead of position index.
.. versionchanged:: 3.6
Added the *module* parameter.
.. versionchanged:: 3.7
Remove the *verbose* parameter and the :attr:`_source` attribute.
.. doctest::
:options: +NORMALIZE_WHITESPACE
@ -878,15 +877,6 @@ field names, the method and attribute names start with an underscore.
>>> for partnum, record in inventory.items():
... inventory[partnum] = record._replace(price=newprices[partnum], timestamp=time.now())
.. attribute:: somenamedtuple._source
A string with the pure Python source code used to create the named
tuple class. The source makes the named tuple self-documenting.
It can be printed, executed using :func:`exec`, or saved to a file
and imported.
.. versionadded:: 3.3
.. attribute:: somenamedtuple._fields
Tuple of strings listing the field names. Useful for introspection