Honestly, I don't see the value in a thin object-oriented wrapper around heapq functions. I'm a big -1 on the idea.
I'm the author of sortedcontainers ( https://pypi.python.org/pypi/sortedcontainers/) so I interact with a lot of people using sorted collections types. My observations show folk's needs tend to fit a bimodal distribution. At one end are those who get by with list.sort, bisect, or heapq and they seem to appreciate the simple function-based approach those modules provide. At the other end are those who want a SortedList data type and we have some good options on PyPI and some good building-blocks in the standard library.
Personally, I think "sorted", "bisect" and "heapq" in the standard library are brilliant examples of the Python-way or "zen." I've learned a lot by studying their code and I encourage others to do the same. Just because something can be object-oriented doesn't mean it should be. There's a lot to be said for simplicity. I also think Nick's arguments are valid but I don't find them convincing.
What I think would be sufficient is a "See also:" blurb like that under https://docs.python.org/3/library/bisect.html#bisect.insort which also references SortedContainers at http://www.grantjenks.com/docs/sortedcontainers/ and the same blurb on heapq. I think that would be a reasonable next-step before we include any new data type in the standard library.
On Wed, Nov 22, 2017 at 8:05 PM, Nick Coghlan email@example.com wrote:
On 22 November 2017 at 11:00, Chris Angelico firstname.lastname@example.org wrote:
So the question is more: why, with Python being the way it is, do the heap functions operate on a list? I think heapq.heapify is the answer: in linear time, it heapifies a list *in place*.
I don't think there's any reason to have *both* interfaces to the heap functionality, but it certainly isn't illogical to try to treat a heap as a thing, and therefore have a Heap type.
Right, the parallel here is that we have a "heapq" module for the same reason that we have list.sort(), sorted(), and the bisect module, rather than a single "SortedList" type. https://code.activestate.com/ recipes/577197-sortedcollection/ then provides an example of how to combine those into a "SortedCollection" type.
That said, I'm still in favour of adding an object-oriented wrapper to either `collections` or the `heapq` module for all the classic OO reasons:
- it makes it easier to reliably maintain the heap invariant (just drop
your list reference after passing it to the heap wrapper)
- it gives both human readers and static code analysers more information
to work with ("this is a heap" rather than "this is a list")
- it provides a hook for improved interactive help on heap instances
I don't have any great concerns about potential confusion - the OO wrapper will be easy enough to use that anyone that's unsure will likely gravitate towards that, while the lower level `heapq` functions will remain available for folks writing their own heap implementations.
This effect would likely be even more pronounced if the OO wrapper were made available as `collections.Heap` (`collections` already imports the `heapq` module for use in the Counter implementation).
-- Nick Coghlan | email@example.com | Brisbane, Australia
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