[ruby-core:93156] [Ruby trunk Bug#15807] Range#minmax is slow and never returns for endless ranges

[janosch84@gmail.com]

Issue #15807 has been updated by janosch-x (Janosch Müller).


jeremyevans0 (Jeremy Evans) wrote:
> I think this is a bug we should fix, even if it breaks code relying on this bug ("all bug fixes are incompatibilities" :)).

Yes, it is a bit reminiscent of https://xkcd.com/1172/ :)

> Does anyone have an opinion on whether `minmax` should call overridden `min` and `max` methods?  Or do we expect if you override `min` or `max`, you should also override `minmax`?  I don't have a strong opinion either way.

Other classes including Enumerable also require `minmax` to be overridden individually. `Set` or `SortedSet` are examples from the stdlib. So I guess it would be more consistent to call the C functions.


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Bug #15807: Range#minmax is slow and never returns for endless ranges
https://bugs.ruby-lang.org/issues/15807#change-78599

* Author: janosch-x (Janosch Müller)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 2.6.3p62
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
current situation:

- `(1..).minmax` runs forever
- `(1..).max` raises "cannot get the maximum of endless range"
- `(1..Float::INFINITY).minmax` runs forever
- `(1..Float::INFINITY).max` returns instantly
- `(1..1_000_000_000).minmax` takes one minute
- `(1..1_000_000_000).max` returns instantly

my suggestion:

- implement `minmax` in range.c, return [`range_min`, `range_max`]
- for endless ranges, this will trigger the same error as `max` does
- delegate to enum (rb_call_super) only if called with a block (?)

i could perhaps provide a PR if you can point me to some information on how to contribute.

cheers!

---Files--------------------------------
range-minmax.patch (2.89 KB)


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