Strange enum

[Rémy Mouëza]

orgoton Wrote:

> I have this in a class:
> 
> enum ActorType:ubyte
> {Unit=0, Building=1, Other=2
> }
> 
> then,
> class Actor
> {
> this()
> {
> assert(this.getType()<5); //THIS FAILS
> }
> (...)
> public final ActorType type=ActorType.Other;
> protected ubyte getType()
> {
> return cast(ubyte)type;
> }
> 
> }
> 
> In a static constructor, an Actor is created to test another class, and the program ends in an assert error.

In Java, one declare constants with final. In D we use the const keyword. Note that this has nothing to do with C++ const type qualifier. There is a certainly a bunch of code in your program that assign a new value to your Actor.type variable. Using const, you'll get a compile time error. 
final is use to explicitly ask the D compiler to make a non polymorphic method (C++ virtual function): by default the D compiler calculate what should be polymorphic or not and optimises in consequences. 

I hope this information helps, 


import std.stdio ;

class ConsoleOutput
{
    this () {}

    ConsoleOutput opShl (T) ( T something )
    {   
        writef ( something );
        return this ;
    }
}

ConsoleOutput cout ;

static this ()
{
    cout = new ConsoleOutput ;
}

enum ActorType : ubyte
{
    Unit = 0, 
    Building = 1, 
    Other = 2
}

class Actor
{
    this ()
    {
        cout << "constructor " << \n ;
        cout << this.getType () << \n ;

        this.type = cast ( ActorType ) 10 ; // without const Ok, with const: compile time error. 
        assert ( this.getType () < 5, "problem" ); //THIS FAILS
    }
    //public final ActorType type = ActorType.Other ;
    public const ActorType type = ActorType.Other ;
    
    protected ubyte getType()
    {
        cout << "getType ()" \n ;
        return cast(ubyte)type;
    }

}

void main ()
{
    cout << "main" \n ; 
    auto actor = new Actor ;
}