castFrom

1 // Regular cast, which has been verified to be legal by the programmer:
2 {
3     long x;
4     auto y = cast(int) x;
5 }
6 
7 // However this will still compile if 'x' is changed to be a pointer:
8 {
9     long* x;
10     auto y = cast(int) x;
11 }
12 
13 // castFrom provides a more reliable alternative to casting:
14 {
15     long x;
16     auto y = castFrom!long.to!int(x);
17 }
18 
19 // Changing the type of 'x' will now issue a compiler error,
20 // allowing bad casts to be caught before it's too late:
21 {
22     long* x;
23     static assert(
24         !__traits(compiles, castFrom!long.to!int(x))
25     );
26 
27     // if cast is still needed, must be changed to:
28     auto y = castFrom!(long*).to!int(x);
29 }