CODEWITHSUNDEEP
crystal-lang
Oleh Sobchuk
Oleh Sobchuk

Reputation: 3722

Crystal method return multiple values

Can Crystal-lang method return multiple values with specific type?

I know that it can be implemented in this way:

def my_method(arg_1 : Int, arg_2 : String) : Tuple
  return arg_1, arg_2
end

res_1, res_2 = my_method(1, "1")

but it also work if I do:

result = my_method(1, "1") #=> {1,"2"}

but can I do somethink like in Go-lang

def my_method(arg_1 : Int, arg_2 : String) : Int, String
  return arg_1, arg_2
end

???

Thanks!

Upvotes: 4

Views: 981

Answers (1)

asterite
asterite

Reputation: 2926

Crystal methods can only return one value. The way to "return multiple values" is by returning a tuple and then, if you want, immediately unpack it at the call site, like what you did.

If you want to specify the return type you can do:

def my_method(arg_1 : Int, arg_2 : String) : {Int32, String}
  return arg_1, arg_2
end

Or (the same, just another syntax):

def my_method(arg_1 : Int, arg_2 : String) : Tuple(Int32, String)
  return arg_1, arg_2
end

You can also use a shorter syntax to return multiple values:

def my_method(arg_1 : Int, arg_2 : String)
  {arg_1, arg_2}
end

That is, doing return 1, 2 is internally the same as returning the tuple {1, 2}.

In the end, it doesn't really matter how this is implemented, maybe in Go the function doesn't really return two values but passes pointers or something like that, and then in assembly there aren't even functions, so what matters if you can return multiple things and then get them all at once, somehow.

Upvotes: 7

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