Feature #20793: Allow Multiple Arguments for the .is_a? Method

• Status: Rejected
• Assignee: -
• Target version: -

[artemb (Artem Borodkin)]

I propose allowing multiple arguments to be passed to the .is_a? Method imply "OR" semantics:

name.is_a? String, Symbol

Currently, we need to write the following to achieve the same functionality:

[String, Symbol].include?(name.class)

[nobu (Nobuyoshi Nakada)]

Also kind_of? method?

[Eregon (Benoit Daloze)]

I think pattern matching should be used here instead of making is_a? more complicated:

irb(main):001:0> name = :abc
=> :abc
irb(main):002:0> name in String | Symbol
=> true
irb(main):003:0> name = 42
=> 42
irb(main):004:0> name in String | Symbol
=> false

is_a? is deeply optimized so accepting multiple arguments would likely make it slower or complicate things significantly.

[artemb (Artem Borodkin)]

Eregon (Benoit Daloze) wrote in #note-2:

I think pattern matching should be used here instead

Very nice, thank you!

If kind_of? (and alias is_a?) has a strong implementation optimization, I agree that this is not so important enhancement.

[matz (Yukihiro Matsumoto)]

• Status changed from Open to Rejected

is_a?(A, B) can be read as is_a?(A) || is_a?(B) or is_a?(A) && is_a?(B). This ambiguity might lead to less readability.

Matz.