Something *should* be object oriented with the functions in question all operate on the same data type, and in particular, those functions/verbs *are only well defined for that type*. heapq.heappush(list-not-heap, item) is perfectly valid code in the current interface, but doesn't make any sense at all. And list.sort is *not* function based, it's an object oriented method. sorted() provides the same functionality for other types, given that it's a well defined function for a wide variety of sequences (unlike heappush). (list.sort is a method because unlike sorted(), it operates inplace, and is thus only meaningful for mutable, "complete" (all in memory, not "lazy") sequences -- i.e., a list.)

I've never used bisect, so I'll refrain from commenting on it.

At the end of the day, the patch proposed is merely a wrapper around the functional approach; you are welcome to continue using it as you like, it's not going anywhere. I would propose that the docs put the OOP version first though.

On Wed, Nov 22, 2017 at 11:11 PM, Grant Jenks <> wrote:
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 ( 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 which also references SortedContainers at 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 <> wrote:
On 22 November 2017 at 11:00, Chris Angelico <> 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. 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   |   |   Brisbane, Australia

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