[ruby-core:93944] [Ruby master Bug#16026] `Set#count` performance issues

[ruby-core:93944] [Ruby master Bug#16026] `Set#count` performance issues

[samuel]

Issue #16026 has been reported by ioquatix (Samuel Williams).

----------------------------------------
Bug #16026: `Set#count` performance issues
https://bugs.ruby-lang.org/issues/16026

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
* Assignee: knu (Akinori MUSHA)
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
`Set#size` is O(1), but `Set#count` is O(N).

I would like to add `alias count size` to `class Set`

Is it okay?



-- 
https://bugs.ruby-lang.org/

[ruby-core:93945] [Ruby master Bug#16026] `Set#count` performance issues

[hanmac]

Issue #16026 has been updated by Hanmac (Hans Mackowiak).


technically `Set#count` comes from `Enumerable`, where it has support for this too

```
enum.count(item)           -> int
enum.count { |obj| block } -> int
```

so i don't think Set should make `#count` work like `#size`

----------------------------------------
Bug #16026: `Set#count` performance issues
https://bugs.ruby-lang.org/issues/16026#change-80131

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
* Assignee: knu (Akinori MUSHA)
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
`Set#size` is O(1), but `Set#count` is O(N).

I would like to add `alias count size` to `class Set`

Is it okay?



-- 
https://bugs.ruby-lang.org/

[ruby-core:93950] [Ruby master Bug#16026] `Set#count` performance issues

[samuel]

Issue #16026 has been updated by ioquatix (Samuel Williams).


I understand and I agree with your logic.

Maybe it's worth considering, `#count` with no arguments can invoke `#size`. What do you think?

----------------------------------------
Bug #16026: `Set#count` performance issues
https://bugs.ruby-lang.org/issues/16026#change-80140

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
* Assignee: knu (Akinori MUSHA)
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
`Set#size` is O(1), but `Set#count` is O(N).

I would like to add `alias count size` to `class Set`

Is it okay?



-- 
https://bugs.ruby-lang.org/

[ruby-core:93959] [Ruby master Bug#16026] `Set#count` performance issues

[jean.boussier]

Issue #16026 has been updated by byroot (Jean Boussier).


> Maybe it's worth considering, #count with no arguments can invoke #size. What do you think?

Since it's what Array does (`rb_ary_count `), it would make sense to do the same in `set.rb` IMHO.


----------------------------------------
Bug #16026: `Set#count` performance issues
https://bugs.ruby-lang.org/issues/16026#change-80150

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
* Assignee: knu (Akinori MUSHA)
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
`Set#size` is O(1), but `Set#count` is O(N).

I would like to add `alias count size` to `class Set`

Is it okay?



-- 
https://bugs.ruby-lang.org/

[ruby-core:94316] [Ruby master Bug#16026] `Set#count` performance issues

[samuel]

Issue #16026 has been updated by ioquatix (Samuel Williams).


I was okay with changing my implementation to use `#size` - which is what I've done. However, I don't think there is anything wrong with optimising this use case if it doesn't add any overhead to existing use case. Because `Array` does it too, it makes me think it's not a completely stupid idea.

----------------------------------------
Bug #16026: `Set#count` performance issues
https://bugs.ruby-lang.org/issues/16026#change-80677

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
* Assignee: knu (Akinori MUSHA)
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
`Set#size` is O(1), but `Set#count` is O(N).

I would like to add `alias count size` to `class Set`

Is it okay?



-- 
https://bugs.ruby-lang.org/

[ruby-core:94322] [Ruby master Bug#16026] `Set#count` performance issues

[knu]

Issue #16026 has been updated by knu (Akinori MUSHA).


I agree that the `return size if !block_given? && respond_to?(:size)` logic should belong to Enumerable.

----------------------------------------
Bug #16026: `Set#count` performance issues
https://bugs.ruby-lang.org/issues/16026#change-80709

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
* Assignee: knu (Akinori MUSHA)
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
`Set#size` is O(1), but `Set#count` is O(N).

I would like to add `alias count size` to `class Set`

Is it okay?



-- 
https://bugs.ruby-lang.org/

[ruby-core:94325] [Ruby master Bug#16026] `Set#count` performance issues

[hanmac]

Issue #16026 has been updated by Hanmac (Hans Mackowiak).


it might not be able to be generic in Enumerable

for example an Widget might be Enumerable with the child widgets, but its size would be `[width, height]`

----------------------------------------
Bug #16026: `Set#count` performance issues
https://bugs.ruby-lang.org/issues/16026#change-80713

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
* Assignee: knu (Akinori MUSHA)
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
`Set#size` is O(1), but `Set#count` is O(N).

I would like to add `alias count size` to `class Set`

Is it okay?



-- 
https://bugs.ruby-lang.org/

[ruby-core:94813] [Ruby master Bug#16026] `Set#count` performance issues

[samuel]

Issue #16026 has been updated by ioquatix (Samuel Williams).

Status changed from Open to Rejected

Given the discussion, I'm okay if we just reject this feature. @knu it's up to you if you want to implement it or not. Even thought it can make sense from one POV, the correct solution for most users is just to use `#size` when it's available, rather than making `#count` more complicated implementation (and potentially slower).

Ultimately, it was my fault for not understanding `#count`.

----------------------------------------
Bug #16026: `Set#count` performance issues
https://bugs.ruby-lang.org/issues/16026#change-81434

* Author: ioquatix (Samuel Williams)
* Status: Rejected
* Priority: Normal
* Assignee: knu (Akinori MUSHA)
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
`Set#size` is O(1), but `Set#count` is O(N).

I would like to add `alias count size` to `class Set`

Is it okay?



-- 
https://bugs.ruby-lang.org/