I'm just starting to play around with the sorbet gem. I have a method that expects and returns an array of objects. The thing is, the length of the array is varied. How can I type check the method? I keep getting Expected type [Object], got array of size 2
Here's my method
sig { params(foo: Array[Object]).returns(Array[Object]) }
def bar(foo)
# code to modify some of the attributes
end
tl;dr You have a syntax error. Use T::Array[Object] (not Array[Object]).
You're using incorrect type syntax for arrays:
# typed: strict
extend T::Sig
sig { params(foo: Array[Object]).returns(Array[Object]) }
def bar(foo)
# code to modify some of the attributes
end
The errors show:
editor.rb:5: Use T::Array[...], not Array[...] to declare a typed Array https://srb.help/5026
5 |sig { params(foo: Array[Object]).returns(Array[Object]) }
^^^^^^^^^^^^^
Note:
Array[...] will raise at runtime because this generic was defined in the standard library
Autocorrect: Use `-a` to autocorrect
editor.rb:5: Replace with T::Array
5 |sig { params(foo: Array[Object]).returns(Array[Object]) }
^^^^^
editor.rb:5: Use T::Array[...], not Array[...] to declare a typed Array https://srb.help/5026
5 |sig { params(foo: Array[Object]).returns(Array[Object]) }
^^^^^^^^^^^^^
Note:
Array[...] will raise at runtime because this generic was defined in the standard library
Autocorrect: Use `-a` to autocorrect
editor.rb:5: Replace with T::Array
5 |sig { params(foo: Array[Object]).returns(Array[Object]) }
^^^^^
Errors: 2
Why is it like this?
The [] method on Array has special meaning, but Sorbet uses [] for generic type arguments. To get around that, Sorbet uses the T:: namespace for certain generic classes in the standard library:
→ https://sorbet.org/docs/stdlib-generics
What's happening in your case is that this code:
Array[Object]
is equivalent to having written this:
[Object]
(i.e., "make an array of length one containing the value Object"). [Object] in Sorbet happens to be the way to express a 1-tuple.