How polymorphism work in D?

[rikki cattermole]

On 06/11/2019 6:43 PM, OiseuKodeur wrote:
> I have this
> 
> ```
> import std.stdio : writeln;
> 
> abstract class Foo { }
> 
> class Bar : Foo
> {
>      float value;
> 
>      this(float t_value) { value = t_value; }
> }
> 
> class Baz : Foo
> {
>      string name;
> 
>      this(string t_name) { name = t_name; }
> }
> 
> void main()
> {
>      Foo foo = new Bar(10);
> 
>      if (/* typeof foo == Bar */)

if (Bar bar = cast(Bar)foo)
	bar.value.writeln;

>          foo.value.writeln;
>      else if (/* typeof foo == Baz */)

else if (Baz baz = cast(Baz)foo)
	baz.name.writeln;

>          foo.name.writeln;
> 
>      foo.writeln;
> }
> ```
> 
> I don't understand how i can differentiate between Bar and Baz and to 
> get their attributes