On 31/03/2016 12:58, Marco Sulla via Python-list wrote:
On 31 March 2016 at 04:40, Steven D'Aprano <st...@pearwood.info> wrote:
Enough of the hypothetical arguments about what one could do or might do.
Let's see a concrete example of actual real world code used in production,
not a mickey-mouse toy program, where it is desirable that adding or
deleting one key will modify the rest of the keys in the mapping.
1. the example was for confuting your assertion that an implementation
of sequences as extended classes of maps violate the map contract.
2. I already linked a real-world example previously. Google it and you
can find tons of examples like that.
On 31 March 2016 at 04:44, Steven D'Aprano <st...@pearwood.info> wrote:
for a, b in zip(spam, eggs):
# do some stuff, sometimes assign x[a] or b[a] or who knows what?
Does this mean that "lists, dicts and zip" should all support the same
interface?
I do not understand what you mean with this example. A zip object is
not a sequence nor a map. My definition of sequences as "ordered maps
with integer keys that start from zero and have no gaps" is perfectly
valid as I demonstrated to you, while zip objects have nothing in
common with sequences and maps, apart the fact they are all iterables.
The definition of sequence is given here
https://docs.python.org/3/glossary.html#term-sequence.
<quote>
An iterable which supports efficient element access using integer
indices via the __getitem__() special method and defines a __len__()
method that returns the length of the sequence. Some built-in sequence
types are list, str, tuple, and bytes. Note that dict also supports
__getitem__() and __len__(), but is considered a mapping rather than a
sequence because the lookups use arbitrary immutable keys rather than
integers.
The collections.abc.Sequence abstract base class defines a much
richer interface that goes beyond just __getitem__() and __len__(),
adding count(), index(), __contains__(), and __reversed__(). Types that
implement this expanded interface can be registered explicitly using
register().
</quote>
As this is a Python list the above definition clearly takes priority
over your definition, so can you please take this discussion offline,
thanks.
--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.
Mark Lawrence
--
https://mail.python.org/mailman/listinfo/python-list
