Splating on case ... when statement get ` unexpected token: "*"` error

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1 
ary = {"foo", "bar"}

case "bar"
when *ary
  puts "1"
else
  puts "2"
end

In 1.cr:4:6

 4 | when *ary
          ^
Error: unexpected token: "*"

I just like to do things like this in Ruby.

ary = ["foo", "bar"]

case "bar"
when *ary
  puts "1"
else
  puts "2"
end
# => 1

Thanks.

2

This is the Crystal way:

if ary.includes?("bar")
  puts "1"
else
  puts "2"
end
3

I guess it would make sense to have it as a language feature. That said, I never used it. I don’t think it’s that common or useful. So maybe not… it might even be confusing.

4

surprise, I used it regularly, my several gem and project both use this splating.

ary = {"foo", "bar"}

case "bar"
when *ary
  puts "1"
else
  puts "2"
end

same as

case "bar"
when *{"foo", "bar"}
  puts "1"

Same as

case "bar"
when "foo", "bar"
  puts "1"

Why you think this confusing? :smile:

5

I get answer from Blacksmoke16 in this closed issue

Following is the accepted answer:

ary = {"foo", "bar"}

case "bar"
when .in? ary
  puts "1"
else
  puts "2"
end
1 Like