[Python-ideas] unify usage of mutable and immutable objects
mlet_it_bew at 126.com
Tue Feb 28 18:47:35 EST 2017
> A hypothetical frozenset.pop() is also necessarily O(N). It needs to copy N-1 elements into the new (smaller) frozenset object. So this isn't an argument.
Pop tuple/frozenset(standard one) gain no benefit. # O(n)
It is a different story for balanced tree. # O(log n)
> Sounds like `collections.deque` might be what you want (for concurrency, not for immutability). But a local copy will require, by definition, a *copy* operation either way.
My intent is to unify "SET" interface, not for to using deque.
I want something that is SET can use anywhere regardless mutable or not.
And the idiom SHOULD work for other type.
WHY set.add / list.sort return None?
if return self, someone may think it don't modify the orignal object.
so, mutable object will have different methods.
Such differences are good UNLESS we want to ignore it explictly.
We need a uniform way to make a interface suitable for both cases.
At 2017-03-01 07:14:33, "David Mertz" <mertz at gnosis.cx> wrote:
On Tue, Feb 28, 2017 at 2:57 PM, 语言破碎处 <mlet_it_bew at 126.com> wrote:
1) coverting to set or list is O(n) in time
A hypothetical frozenset.pop() is also necessarily O(N). It needs to copy N-1 elements into the new (smaller) frozenset object. So this isn't an argument.
2) if I have to keep the old copy,
standard set solution will be O(n) both in time and space!
Again, nothing gained here. Same applies to frozenset.pop() (assuming it returns both the item popped and a reduced set). If you just want "something from frozenset" without creating a new almost-copy frozenset, that is spelled `next(iter(fs))`.
1) priority queue:
insert and pop occur
2) share immutable data to difference subroutines:
each one can modify local copy safely and concurrency.
Sounds like `collections.deque` might be what you want (for concurrency, not for immutability). But a local copy will require, by definition, a *copy* operation either way.
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