Re: Implicit conversion with ctor like C++

[Meta via Digitalmars-d-learn]

On Tuesday, 8 September 2015 at 19:23:47 UTC, Pierre wrote:
Hi everybody,
I would like to use implicit conversion like this:

//Sample class
class MyClass
{
   this(string MyValue){...}
}

//Called function
void MyFunction(Foo MyFoo){}

void main()
{
  MyFunction("Hello World!"); //Failed : MyFunction not 
callable...
}

I saw in forum this is OK because D doesn't do implicit 
conversion with ctor like C++
But how can I do ? May I use alias ?

Thank you for your attention.

No, as far as I know, D does not support implicit construction of 
classes or structs. There is *some* implicit conversion allowed, 
but in the opposite direction.

struct Test
{
    string s;
    alias s this;

    //Necessary for nice construction syntax
    this(string s) { this.s = s; }
}

void foo(string s)
{
    writeln(s);
}

void main()
{
    Test t = "asdf";
    foo(t); //Prints "asdf"
}

So with alias this, you can pass a Test to a function expecting a 
string, but not vice-versa.