A question about postblit constructor

[Ferhat Kurtulmuş]

On Tuesday, 5 November 2019 at 10:13:59 UTC, Mike Parker wrote:
> On Tuesday, 5 November 2019 at 08:47:05 UTC, Ferhat Kurtulmuş 
> wrote:
>
>> value of int which is 0. I wonder how new memory is allocated 
>> without an explicit malloc here. Sorry for this noob question 
>> in advance, I could not find any doc mentioning a similar case.
>>
>
>>     int* vals = cast(int*)malloc(len * S.sizeof);
>>     vals[0] = 4;
>>     vals[1] = 5;
>>
>>     S s1 = S(vals, len);
>>
>>     S s2 = s1;
>>
>>     writeln(s2.vals[0]);
>
>       writeln(s2.vals);
>       writeln(s1.vals);
>
>> }
>
> https://run.dlang.io/is/D0nfeT

Yep, it is obvious that my code is wrong. s1 and s2 point to the 
same memory address. I could obtain my desired behavior with copy 
constructor. The documentation also say "WARNING: The postblit is 
considered legacy and is not recommended for new code. Code 
should use copy constructors defined in the previous section".

struct S {
     int* vals;
     size_t length;

     this(ref return scope S another) {
     	vals = cast(int*)malloc(another.length * S.sizeof);
         memcpy(vals, another.vals, another.length * S.sizeof);
         writeln("copied");
     }
     this(int* vls, size_t len){
         vals = vls;
         length = len;
     }

     ~this(){
      	free(vals);
         writeln("freedooom!");
     }
}