Issue #13820 has been reported by williamn (William Newbery).
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Feature #13820: Add a nill coalescing operator
https://bugs.ruby-lang.org/issues/13820
* Author: williamn (William Newbery)
* Status: Open
* Priority: Normal
* Assignee:
* Target version:
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It would be nice if Ruby had an operator that only considered `nil` as false, like the null coalescing operators or "Logical Defined-Or operator" (Perl) found in some other languages. Ive seen things like `//` and `//=`m `??` and `??=`, or `?:` used for this.
This would work like `||` and `||=` for short circuiting etc. except that only `nil` is considered a false condition.
While Ruby considers only "false" and "nil" as false, with everything else true ("", [], {}, etc.) I still find occasionally people trip up when using logical or, `||` and `||=` when the value may be false.
```ruby
a = 0 || 55 # = 0 Ruby already considers 0, "", etc. as true (oter languages do differ a lot here)
a = 0 ?? 55 # = 0 So no change here
a = nil || 55 # = 55, nil is false so right side is evaulated.
a = nil ?? 55 # = 55, again no change
a = false || 55 # = 55, however false is false for logical or
a = false ?? 55 # = false, but its still a non-nil value
```
For example when doing things like:
```ruby
def lazy
@lazy ||= compute_this
end
def fetch(id, **opts)
host = opts[:host] || default_host
https = opts[:https] || true
port = opts[:port] || (https ? 443 : 80)
...
```
Normally the intention is to use a default value or compute an action if no value is provided, which if the value may be false then requires special handling, or sometimes is missed and results in a bug.
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