On Mon, 24 Mar 2014 23:53:12 +1100, Chris Angelico wrote:
> On Mon, Mar 24, 2014 at 11:36 PM, Marko Rauhamaa <ma...@pacujo.net>
> wrote:
>>> def get_oneth_element_index(item):
>>> return item[1].index
>>> L.sort(key=get_oneth_element_index)
>>>
>>> Or do you just shortcut the whole thing by inlining it?
>>>
>>> L.sort(key=lambda item:item[1].index)
>>
>> I still prefer the "def" variant. It even allows you to clarify the
>> meaning of the tuple slot by using a nicer name.
>
> It's the index of element 1. What more do you need to know? Is it
> actually any help to give that a name? All you gain is a chance for the
> name, the purpose, and the functionality to come into disagreement.
# Magic constants are wicked. Never use a constant without naming it.
ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L = 1
# <summary>
# key func used when sorting L, returns item's 1th elem index method
# </summary>
# <function_name>
# _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L
# </function_name>
# <author>Steven D'Aprano</author>
# <date_created>2014-03-25</date_created>
# <date_modified>2014-03-25</date_modified>
# <revision>1</revision>
# <param name="item">item to be sorted</param>
# <returns>index method of the oneth element</returns>
# <raises>NameError</raises> # FIXME can this fail any other way?
def _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L(item):
"""Private key function for sorting list L.
Returns the index method of element 1 of the given item.
Example of use:
>>> item = (None, '')
>>> _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L(item)
<built-in method index of str object at ...>
Relies on global constant ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L.
May raise NameError if that constant is missing.
Warning: do not use this for anything else.
"""
return item[ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L].index
L.sort(key=_get_oneth_element_index_to_use_as_keyfunc_when_sorting_L)
del _get_oneth_element_index_to_use_as_keyfunc_when_sorting_L
# Better to be safe than sorry.
del ELEMENT_TO_USE_FOR_INDEXING_WHEN_SORTING_L
Definitely being paid by the line :-)
--
Steven D'Aprano
http://import-that.dreamwidth.org/
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