Feature #19588: Allow Comparable#clamp(min, max) to accept nil as a specification - Ruby master - Ruby Issue Tracking System

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Feature #19588

closed

Allow Comparable#clamp(min, max) to accept nil as a specification

Added by kyanagi (Kouhei Yanagita) about 1 year ago. Updated 5 months ago.

Status:

Closed

Assignee:

Target version:

[ruby-core:113180]

Description

Comparable#clamp(min, max) (with two arguments) accepts nil. This behaves the same as beginless/endless Range.

5.clamp(nil, 0)   # => 0
5.clamp(10, nil)  # => 10
5.clamp(..0)      # => 0
5.clamp(10..)     # => 10

This behavior is not documented. Presumably, this was not introduced intentionally.

The old Rubies did not accept accept a Range argument.

In Ruby 2.7, accepting Range as an argument was introduced.
At that time, the approach of passing nil as a two-argument method was also discussed but not adopted,
and using Range was chosen instead. https://bugs.ruby-lang.org/issues/14784

However, in Ruby 3.0, the behavior of clamp has changed to accept nil.
This change is not documented in the NEWS or the documentation for clamp,
and I believe that it was not an intentional change.

% docker run -it --rm rubylang/all-ruby env ALL_RUBY_SINCE=ruby-2.4.0 ./all-ruby -e "p 5.clamp(0, nil)"
ruby-2.4.0          -e:1:in `clamp': comparison of Integer with nil failed (ArgumentError)
                        from -e:1:in `<main>'
                exit 1
...
ruby-2.7.8          -e:1:in `clamp': comparison of Integer with nil failed (ArgumentError)
                        from -e:1:in `<main>'
                exit 1
ruby-3.0.0-preview1 5
...
ruby-3.2.2          5

It seems that https://github.com/ruby/ruby/commit/a93da4970be44a473b7b42e7516eb2663dece2c3 brought about this change.

How about making the current behavior a specification?
It has been three years since the behavior changed, and I don't see much point in prohibiting nil now.

https://github.com/ruby/ruby/pull/7692 updates the documentation.