• Nicholas Wilson (14/14) Feb 25 2016 struct A
• cym13 (9/23) Feb 25 2016 As you did:
• Nicholas Wilson (4/30) Feb 25 2016 fails to compile
• cym13 (4/36) Feb 26 2016 What compiler and version are you using ? Because I literally
• Adam D. Ruppe (9/23) Feb 25 2016 Use a constructor for A instead of trying to write to one

Nicholas Wilson <iamthewilsonator hotmail.com> writes:

struct A
{
      const (void *) p;
}

struct B
{
     A    a;
     this(void * _p)
     {
         a.p = _p;
     }
}

I cannot change the definition of A
how do I initialise b.a.p?

cym13 <cpicard openmailbox.org> writes:

On Friday, 26 February 2016 at 02:32:44 UTC, Nicholas Wilson 
wrote:
 struct A
 {
      const (void *) p;
 }

 struct B
 {
     A    a;
     this(void * _p)
     {
         a.p = _p;
     }
 }

 I cannot change the definition of A
 how do I initialise b.a.p?

As you did:

     void main() {
         int i = 42;
         B b = B(&i);
         int* p = cast(int*)b.a.p;
         assert(*p == 42);
     }

Nicholas Wilson <iamthewilsonator hotmail.com> writes:

On Friday, 26 February 2016 at 02:48:35 UTC, cym13 wrote:
 On Friday, 26 February 2016 at 02:32:44 UTC, Nicholas Wilson 
 wrote:
 struct A
 {
      const (void *) p;
 }

 struct B
 {
     A    a;
     this(void * _p)
     {
         a.p = _p;
     }
 }

 I cannot change the definition of A
 how do I initialise b.a.p?

 As you did:

     void main() {
         int i = 42;
         B b = B(&i);
         int* p = cast(int*)b.a.p;
         assert(*p == 42);
     }

         a.p = _p;

fails to compile
fixed by
a = typeof(a)(_p);

cym13 <cpicard openmailbox.org> writes:

On Friday, 26 February 2016 at 03:18:02 UTC, Nicholas Wilson 
wrote:
 On Friday, 26 February 2016 at 02:48:35 UTC, cym13 wrote:
 On Friday, 26 February 2016 at 02:32:44 UTC, Nicholas Wilson 
 wrote:
 struct A
 {
      const (void *) p;
 }

 struct B
 {
     A    a;
     this(void * _p)
     {
         a.p = _p;
     }
 }

 I cannot change the definition of A
 how do I initialise b.a.p?

 As you did:

     void main() {
         int i = 42;
         B b = B(&i);
         int* p = cast(int*)b.a.p;
         assert(*p == 42);
     }

         a.p = _p;

 fails to compile
 fixed by
 a = typeof(a)(_p);

What compiler and version are you using ? Because I literally 
just copied your example and added my main and got no error.

Adam D. Ruppe <destructionator gmail.com> writes:

On Friday, 26 February 2016 at 02:32:44 UTC, Nicholas Wilson 
wrote:
 struct A
 {
      const (void *) p;
 }

 struct B
 {
     A    a;
     this(void * _p)
     {
         a.p = _p;
     }
 }

 I cannot change the definition of A
 how do I initialise b.a.p?

Use a constructor for A instead of trying to write to one 
specific member:

a = A(_p);

const variable must be initialized in constructors. Structs have 
automatically defined constructors that take all the member 
variables so even if it isn't explicitly written, you can still 
do this.