On Thursday, 21 May 2015 at 09:06:59 UTC, Timothee Cour wrote:
Can I create an instance of A without calling a constructor?
(see below)
Use case: for generic deserialiaztion, when the deserialization
library
encounters a class without default constructor for example (it
knows what
the fields should be set to, but doesn't know how to construct
the object).
class A{
int x=2;
this(int x){
this.x=x;
}
}
This came up here:
https://github.com/msgpack/msgpack-d/issues/54#issuecomment-104136148
I provide some hacky solution for that in that thread but I
suspect it's
not safe and something is missing.
based on this:
https://github.com/D-Programming-Language/druntime/blob/6698ee21d4eb00ec2e8c621993359d235618df75/src/rt/lifetime.d#L71
you can create an instance without calling the constructor like
this:
---
CT construct(CT, A...)(A a)
if (is(CT == class))
{
auto memory = malloc(typeid(CT).init.length);
memory[0 .. typeid(CT).init.length] = typeid(CT).init[];
return cast(CT) memory;
}
---
actually it only copies the fields with their initial values.
