betterC: new operator

[Basile B.]

On Sunday, 22 November 2020 at 16:58:03 UTC, Basile B. wrote:
> On Sunday, 22 November 2020 at 11:54:01 UTC, Dibyendu Majumdar 
> wrote:
>> I had assumed that new operator is not available in betterC.
>>
>> But in following code, it seems the only way to initialize the 
>> object correctly ... is there another way I am missing? How 
>> should one cleanup objects?
> however note
> 1. not well tested (e.g overloads)
> 2. static init of fields is not done because that really 
> rquires TypeInfo, so a ctor has to be used instead.
>
> But that's a good start to get things done more properly

And the leaks...

More simple solution adapted from

http://dpldocs.info/this-week-in-d/Blog.Posted_2020_07_27.html#zero-runtime-classes

---
#!dmd -betterC
extern(C) int printf(const char*, ...);

extern(C++) class A  {
         int omg() { return 12; }
}

extern(C++) class B : A {
         override int omg() { return 34; }
}

template New(T) {
         pragma(mangle, "_D" ~ T.mangleof[1..$] ~ "6__initZ")
         __gshared extern immutable 
ubyte[__traits(classInstanceSize, T)] initializer;

         T New(ref ubyte[__traits(classInstanceSize, T)] memory) {
                 foreach(idx, ref b; memory) {
                         b = initializer.ptr[idx];
                 }
                 return cast(T) memory.ptr;
         }
}

extern(C) int main() {
         ubyte[__traits(classInstanceSize, A)] buffer;
         A a = New!B(buffer);
         printf("hi %d\n", a.omg());
         return 0;
}
---