• Guenter (32/32) Feb 26 2017 Hi,
• Eugene Wissner (5/37) Feb 26 2017 It should be:
• Guenter (3/5) Feb 26 2017 Thank you.
• Mike Parker (5/9) Feb 26 2017 Structs in D are value types, so you're returning a copy of fext
• Guenter (3/14) Feb 26 2017 Thank you.

Guenter <gbl1 gmx.net> writes:

Hi,

i do not understand where I am wrong in this code. I seems there 
is a missing constructor, but i have no idea where.


module main;


import std.stdio;


struct A_t
{
   int fvalue;


   A_t opCall()
   {
     return this;
   };

    property  int value () { return fvalue; }

    property void value (int avalue) { fvalue = avalue; }
}


struct B_t
{
   A_t  fext;


   int opCall() { return ext.value; };


    property A_t  ext() { return fext; }

    property void ext(A_t aext) { fext = aext; }
}



void main()
{
   B_t   test;


   test.ext.value = 9;
   int t = test();

   assert ( t == 9);   //  t  is always 0 instead of 9.


   readln();
}


cu
Guenter

Eugene Wissner <belka caraus.de> writes:

On Sunday, 26 February 2017 at 11:05:42 UTC, Guenter wrote:
 Hi,

 i do not understand where I am wrong in this code. I seems 
 there is a missing constructor, but i have no idea where.


 module main;


 import std.stdio;


 struct A_t
 {
   int fvalue;


   A_t opCall()
   {
     return this;
   };

    property  int value () { return fvalue; }

    property void value (int avalue) { fvalue = avalue; }
 }


 struct B_t
 {
   A_t  fext;


   int opCall() { return ext.value; };


    property A_t  ext() { return fext; }

    property void ext(A_t aext) { fext = aext; }
 }



 void main()
 {
   B_t   test;


   test.ext.value = 9;
   int t = test();

   assert ( t == 9);   //  t  is always 0 instead of 9.


   readln();
 }


 cu
 Guenter

It should be:
 property ref A_t  ext() { return fext; }

you return a copy of A_t and then change this copy instead of the 
real B_t member.

Guenter <gbl1 gmx.net> writes:

On Sunday, 26 February 2017 at 11:15:21 UTC, Eugene Wissner wrote:
 you return a copy of A_t and then change this copy instead of 
 the real B_t member.


Thank you.
Guenter

Mike Parker <aldacron gmail.com> writes:

On Sunday, 26 February 2017 at 11:05:42 UTC, Guenter wrote:
 Hi,

 i do not understand where I am wrong in this code. I seems 
 there is a missing constructor, but i have no idea where.

    property A_t  ext() { return fext; }

Structs in D are value types, so you're returning a copy of fext 
here and that's what's getting updated with the new value. Try 
this:

ref A_T ext() { return fext; }

Guenter <gbl1 gmx.net> writes:

On Sunday, 26 February 2017 at 11:18:12 UTC, Mike Parker wrote:
 On Sunday, 26 February 2017 at 11:05:42 UTC, Guenter wrote:
 Hi,

 i do not understand where I am wrong in this code. I seems 
 there is a missing constructor, but i have no idea where.

    property A_t  ext() { return fext; }

 Structs in D are value types, so you're returning a copy of 
 fext here and that's what's getting updated with the new value. 
 Try this:

 ref A_T ext() { return fext; }

Thank you.
Guenter