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#16523: improve attrgetter/itemgetter/methodcaller documentation.

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This commit is contained in:
Ezio Melotti 2013-05-08 10:53:11 +03:00
parent c58a3ea72c
commit babc8227cc
2 changed files with 40 additions and 21 deletions
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47
Doc/library/operator.rst
View file

@ -241,13 +241,22 @@ lookups. These are useful for making fast field extractors as arguments for
expect a function argument.
.. function:: attrgetter(attr[, args...])
.. function:: attrgetter(attr)
attrgetter(*attrs)
Return a callable object that fetches *attr* from its operand. If more than one
attribute is requested, returns a tuple of attributes. After,
``f = attrgetter('name')``, the call ``f(b)`` returns ``b.name``. After,
``f = attrgetter('name', 'date')``, the call ``f(b)`` returns ``(b.name,
b.date)``. Equivalent to::
Return a callable object that fetches *attr* from its operand.
If more than one attribute is requested, returns a tuple of attributes.
The attribute names can also contain dots. For example:
* After ``f = attrgetter('name')``, the call ``f(b)`` returns ``b.name``.
* After ``f = attrgetter('name', 'date')``, the call ``f(b)`` returns
``(b.name, b.date)``.
* After ``f = attrgetter('name.first', 'name.last')``, the call ``f(b)``
returns ``(r.name.first, r.name.last)``.
Equivalent to::
def attrgetter(*items):
if any(not isinstance(item, str) for item in items):
@ -267,14 +276,19 @@ expect a function argument.
return obj
The attribute names can also contain dots; after ``f = attrgetter('date.month')``,
the call ``f(b)`` returns ``b.date.month``.
.. function:: itemgetter(item[, args...])
.. function:: itemgetter(item)
itemgetter(*items)
Return a callable object that fetches *item* from its operand using the
operand's :meth:`__getitem__` method. If multiple items are specified,
returns a tuple of lookup values. Equivalent to::
returns a tuple of lookup values. For example:
* After ``f = itemgetter(2)``, the call ``f(r)`` returns ``r[2]``.
* After ``g = itemgetter(2, 5, 3)``, the call ``g(r)`` returns
``(r[2], r[5], r[3])``.
Equivalent to::
def itemgetter(*items):
if len(items) == 1:
@ -313,9 +327,14 @@ expect a function argument.
Return a callable object that calls the method *name* on its operand. If
additional arguments and/or keyword arguments are given, they will be given
to the method as well. After ``f = methodcaller('name')``, the call ``f(b)``
returns ``b.name()``. After ``f = methodcaller('name', 'foo', bar=1)``, the
call ``f(b)`` returns ``b.name('foo', bar=1)``. Equivalent to::
to the method as well. For example:
* After ``f = methodcaller('name')``, the call ``f(b)`` returns ``b.name()``.
* After ``f = methodcaller('name', 'foo', bar=1)``, the call ``f(b)``
returns ``b.name('foo', bar=1)``.
Equivalent to::
def methodcaller(name, *args, **kwargs):
def caller(obj):

14
Modules/operator.c
View file

@ -460,8 +460,8 @@ PyDoc_STRVAR(itemgetter_doc,
"itemgetter(item, ...) --> itemgetter object\n\
\n\
Return a callable object that fetches the given item(s) from its operand.\n\
After, f=itemgetter(2), the call f(r) returns r[2].\n\
After, g=itemgetter(2,5,3), the call g(r) returns (r[2], r[5], r[3])");
After f = itemgetter(2), the call f(r) returns r[2].\n\
After g = itemgetter(2, 5, 3), the call g(r) returns (r[2], r[5], r[3])");
static PyTypeObject itemgetter_type = {
PyVarObject_HEAD_INIT(NULL, 0)
@ -712,9 +712,9 @@ PyDoc_STRVAR(attrgetter_doc,
"attrgetter(attr, ...) --> attrgetter object\n\
\n\
Return a callable object that fetches the given attribute(s) from its operand.\n\
After, f=attrgetter('name'), the call f(r) returns r.name.\n\
After, g=attrgetter('name', 'date'), the call g(r) returns (r.name, r.date).\n\
After, h=attrgetter('name.first', 'name.last'), the call h(r) returns\n\
After f = attrgetter('name'), the call f(r) returns r.name.\n\
After g = attrgetter('name', 'date'), the call g(r) returns (r.name, r.date).\n\
After h = attrgetter('name.first', 'name.last'), the call h(r) returns\n\
(r.name.first, r.name.last).");
static PyTypeObject attrgetter_type = {
@ -844,8 +844,8 @@ PyDoc_STRVAR(methodcaller_doc,
"methodcaller(name, ...) --> methodcaller object\n\
\n\
Return a callable object that calls the given method on its operand.\n\
After, f = methodcaller('name'), the call f(r) returns r.name().\n\
After, g = methodcaller('name', 'date', foo=1), the call g(r) returns\n\
After f = methodcaller('name'), the call f(r) returns r.name().\n\
After g = methodcaller('name', 'date', foo=1), the call g(r) returns\n\
r.name('date', foo=1).");
static PyTypeObject methodcaller_type = {