Add attributes support to New about fusion

[dphfox]

Possible API (implemented as part of the New function):

New "Instance" {
    [Attribute "Foo"] = "bar", -- if a state or computed object, binds to the attribute
    [AttributeChange "Foo"] = function(newValue)
        print("The attribute was changed to:", newValue)
    end
}

[blake-mealey]

I personally prefer the first option as it is very similar to the API for normal properties.

[dphfox]

An alternate possible API from Twitter (adapted from a suggestion by @/bradsharppp):

New "Instance" {
    [Attributes] = {
        Foo = "bar",
        [OnChange "Foo"] = function(newValue)
            print("The attribute was changed to:", newValue)
        end
    }
}

Alternatively, we could keep AttributeChange separate from the Attributes table?

[dphfox]

I personally prefer the first option as it is very similar to the API for normal properties.

Agreed - I don't personally see many use cases where a lot of attributes are being used at once within the context of Fusion, so I think it'd overall be cleaner not to use a nested table.

[Gargafield]

I personally prefer the first option as it is very similar to the API for normal properties.

Agreed - I don't personally see many use cases where a lot of attributes are being used at once within the context of Fusion, so I think it'd overall be cleaner not to use a nested table.

Same here! I think fusion should eliminate the times where you normally in Roact get huge files with lots of scopes.