June 07, 2004
// the classes:
private class Master{}
private class Foo : Master{}
private class Bar : Master{}

public static int main(char[][] args){

 bit isBar;
 bit isFoo;

 // valid and compiles:
 Master a = (isBar) ? (new Bar()) : (new Master());
 Master b = (isFoo) ? (new Foo()) : (new Master());

 // valid, but fails to compile:
 Master c = (isBar) ? (new Bar()) : (new Foo());

 return 0;
}



June 13, 2004
"Thomas Kuehne" <thomas-ThisIsSpam@kuehne.cn> wrote in message news:ca1m8u$2ogp$1@digitaldaemon.com...
> // the classes:
> private class Master{}
> private class Foo : Master{}
> private class Bar : Master{}
>
> public static int main(char[][] args){
>
>  bit isBar;
>  bit isFoo;
>
>  // valid and compiles:
>  Master a = (isBar) ? (new Bar()) : (new Master());
>  Master b = (isFoo) ? (new Foo()) : (new Master());
>
>  // valid, but fails to compile:
>  Master c = (isBar) ? (new Bar()) : (new Foo());

This is not valid. The semantics of the ternary operator stipulate that the expression as a whole has the type of the second sub-expression. Hence, your statement is exactly equivalent to

    Master c = (isBar) ? cast(Bar)(new Bar()) : (new Foo());

which is obviously not valid.

The fix is obvious

    Master c = (isBar) ? cast(Master)(new Bar()) : (new Foo());