From: lpogic via ruby-core <ruby-core@...>
Date: 2025-03-05T09:27:33+00:00
Subject: [ruby-core:121244] [Ruby master Feature#21157] Comparison operator <>

Issue #21157 has been updated by lpogic (��ukasz Pomiet��o).


Such a note in the documentation would certainly be advisable. Could a similar one be added to the `max`, `min` and `minmax` methods?

There is one more issue. I think that someone who sees `(a.y <=> b.y).nonzero?` for the first time will not guess what is going on here without finding `nonzero?` in the documentation. Maybe it would be worth adding an alias for `nonzero?`? Maybe `ordinal`?

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Feature #21157: Comparison operator <>
https://bugs.ruby-lang.org/issues/21157#change-112191

* Author: lpogic (��ukasz Pomiet��o)
* Status: Feedback
----------------------------------------
I propose introducing a comparison operator *<>* which would give the following results:
```ruby
1 <> 2 # => -1
2 <> 1 # => 1
1 <> 1 # => false
1 <> "a" # => true
```

With the help of the new operator, complex ordering expressions could be written explicitly. For example:
```ruby
Point = Struct.new(:x, :y)
array = [Point.new(1, 2), Point.new(6, 4), Point.new(2, 2), Point.new(5, 2)]

array.sort{|a, b| a.y <> b.y || b.x <> a.x || 0 } # => [#<struct Point x=5, y=2>, #<struct Point x=2, y=2>, #<struct Point x=1, y=2>, #<struct Point x=6, y=4>]
```

The `<>` notation may look familiar to sql users, where it means 'not equal'. Defined in the form given it will retain this meaning to some extent:
```ruby
a = b = 1
a_not_equal_b if a <> b
a_equal_b unless a <> b
```



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