struct init property

[Ali Çehreli]

On 08/23/2012 10:15 AM, nocide wrote:
> struct has no default constructor and instances are initialized with the
> init property.
> Can I declare or override the init property for a custom defined struct?
>
You can define the initial values of each member:

struct S
{
     int i = 42;
     double d = 1.5;
}

void main()
{
     assert(S.init == S(42, 1.5));
}

That changes the .init value. You can also define a static opCall() to 
mimic the default constructor. Note that this method does not affect the 
.init value:

struct S
{
     int i;
     double d;

     static S opCall()
     {
         S s;
         s.i = 42;
         s.d = 1.5;
         return s;
     }
}

void main()
{
     assert(S().i == 42);
     assert(S().d == 1.5);

     assert(S.init.i == int.init);
     import std.math;
     assert(isnan(S.init.d));
}

Note that the static opCall() disables calling automatic destructor 
(i.e. the S(1, 2) does not work anymore). I am not sure whether that is 
one of the many struct-related issues at the moment.

Ali