Re: enum scope

[Meta via Digitalmars-d]

On Thursday, 26 January 2012 at 13:23:43 UTC, Trass3r wrote:
It's not type safe in C. But you can wrap it in a struct with 
alias this instead.

Yep, but in D we have strong enums, so why not use them.

Enums aren't as strongly typed as you would think (or as I would 
like). The major problem is that it's incredibly easy to get an 
invalid enum value, even without using a cast.

enum Foo
{
    one = 1,
    two,
    three,
}

enum Bar
{
    first,
    second,
    third,
}

void takesFoo(Foo foo)
{
}

void main()
{
    int n = Foo.one;
    assert(n == 1);
        
    //Luckily, this doesn't compile
    //Foo foo1 = n;

    int[] arr = new int[](3);
    int m = arr[Foo.two];
        
    //Unfortunately, this DOES compile
    Foo foo2 = Foo.one - Foo.two;
    assert(foo2 == -1);
    takesFoo(foo2);
        
    //Fails (thank goodness)
    //takesFoo(Bar.third);
        
    //This actually isn't as bad as it looks.
    //The result is of type int and thus
    //can't be assigned back to a Foo or Bar
    assert(Foo.two - Bar.third == 0);
        
    //Fails
    //Foo foo3 = Foo.two - Bar.second;
        
    //Fails
    //Bar bar = Bar.first - Foo.three;
}