Method/operator-level generics

[SamahParticipant]

I want to be able to do something like this:

Monkey

[crayon-5cb9bd084dbc3502613945 inline="true" ]Namespace test #Import "<std>" Using std.. Function Main:Void() Local foo := New Foo foo.map["mytruck"] = New Truck foo.map["mycar"] = New Car Local car:Car = foo["mycar"] ' implicitly casts to Car Local truck:Truck = foo["mytruck"] ' implicitly casts to Truck Local test:Car = foo["mytruck"] ' implicitly casts to Car, but returns Null since it's the wrong type End Class Foo Field map:StringMap<Vehicle> = New StringMap<Vehicle> Method New() End Operator []<T>:T(name:String) Where T Extends Vehicle Return Cast<T>(map[name]) End End Class Vehicle Method New() End End Class Car Extends Vehicle Method New() End End Class Truck Extends Vehicle Method New() End End

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[crayon-5cb9bd084dbc3502613945 inline="true" ]Namespace test   #Import "<std>"   Using std..   Function Main:Void()   Local foo := New Foo   foo.map["mytruck"] = New Truck   foo.map["mycar"] = New Car     Local car:Car = foo["mycar"] ' implicitly casts to Car   Local truck:Truck = foo["mytruck"] ' implicitly casts to Truck   Local test:Car = foo["mytruck"] ' implicitly casts to Car, but returns Null since it's the wrong type End   Class Foo   Field map:StringMap<Vehicle> = New StringMap<Vehicle>     Method New()   End     Operator []<T>:T(name:String) Where T Extends Vehicle     Return Cast<T>(map[name])   End End   Class Vehicle   Method New()   End End   Class Car Extends Vehicle   Method New()   End End   Class Truck Extends Vehicle   Method New()   End End

[/crayon]

But I get:

Error : Can't find overload for '[](...)' with argument types (string)

Is there a way I can do this?

[Mark SiblyKeymaster]

Generic types are only infered from parameters. If a type can’t be infered from parameters, you need to explicitly specify it, which isn’t supported for operators so you’d need to use something like…

Monkey

Local car:=foo.Get<Car>( "Car" )

1	Local car:=foo.Get<Car>( "Car" )

…instead.

[SamahParticipant]

That’s a pity, some other languages can infer from the return type.
I guess a “Get” method will have to be good enough.

[Author]

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