Re: Library Typedefs are fundamentally broken

[Meta via Digitalmars-d]

On Monday, 22 September 2014 at 09:39:29 UTC, Don wrote:
My feeling is that almost every time when you want to create a 
new type from an existing one, you actually want to restrict 
the operations which can be performed on it. (Eg if you have  
typedef money = double; then money*money doesn't make much 
sense). For most typedefs I think you're better off with 'alias 
this'.

`alias this` doesn't restrict what operations can be performed on 
the supertype.

struct Money
{
        this(double d)
        {
                amount = d;
        }
        
        double amount;
        alias amount this;
}

void main()
{
        //This doesn't compile without a constructor defined
        //that takes a double... I thought alias this took
        //care of that, but apparently not
        Money m = 2.0;
        Money n = m * m;
        assert(n == 4.0);
}