[ruby-core:97279] [Ruby master Feature#15722] `Kernel#case?`

Issue #15722 has been updated by matz (Yukihiro Matsumoto).

Status changed from Open to Feedback

It is not obvious to me that `#case?` is useful. We need a real-world use-case.

* I don't like the name `case?`
* IMO, just use `case` statement

Matz.


----------------------------------------
Feature #15722: `Kernel#case?`
https://bugs.ruby-lang.org/issues/15722#change-84396

* Author: sawa (Tsuyoshi Sawada)
* Status: Feedback
* Priority: Normal
----------------------------------------
I often want to use `===` to match a single object on the right side against multiple objects on the left, as is used in `case`-constructions, just to return a truth value, and end up writing like this:

```ruby
bar # => "bar"
flag1 = case bar; when "foo", "bar", "baz"; true; end # => true
flag2 = case bar; when Symbol, String; true; end # => true
```

I propose `Kernel#case?` that should work like this:

```ruby
bar # => "bar"
bar.case?("foo", "bar", "baz") # => true
bar.case?("qux") # => false
bar.case?(Symbol, String) # => true
bar.case?(Array) # => false
bar.case? # => false
```

It is similar to Rails' `in?`, but it differs from it in that it uses `===` for comparison, not `==`.

Or, alternatively, allowing `Kernel#instance_of?` and `Kernel#kind_of?` to allow multiple arguments may be a compromise.



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

Unsubscribe: <mailto:[e-mail]?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>