Re: How to new a class object in a struct

[Timon Gehr]

On 09/01/2011 04:10 PM, zhang wrote:
Here are some codes:
class AClass
{
     int a = 10;
}

struct AStruct
{
     AClass aclass;

//    this()  // can't do this in a struct
//    {
//        aclass = new AClass()
//    }

     this(AClass aclass_)
     {
         aclass = aclass_;
     }
}


int main(string[] args)
{
     AStruct astruct;
     int a = astruct.aclass.a;
     writefln("%d", a);
     return 0;
}


In D, this() is prohibited in a struct. So
    AStruct astruct
will leave the aclass object to be null. It's not like the way in C++, the 
aclass object will be created automatically.

It always leads some problems when doing porting from C++ to D.

My solution is to use class instead of struct. Then I can create the aclass 
object in this() when I new an AStruct.

Any suggestion?
Thanks.

----------
Zhang<bitwo...@qq.com>



This works:

class AClass
{
    int a = 10;
}

struct AStruct
{
    AClass aclass;

    // this() @disable; // will be in the next DMD release 



    static AStruct opCall()
    {
        return AStruct(new AClass());
    }

    static AStruct opCall(AClass aclass_)
    {
        AStruct result = void;
        result.aclass = aclass_;
        return result;
    }
}


int main(string[] args)
{
    auto astruct = AStruct();
    int a = astruct.aclass.a;
    writefln("%d", a);
    return 0;
}