Struct Constructor Lazy

[Biotronic via Digitalmars-d-learn]

On Wednesday, 12 July 2017 at 11:34:45 UTC, Jiyan wrote:
> Hey,
> yes i did but to be honest i used dmd in debug version.
> The thing about the static one, is that it creates a local 
> object A isnt that a performance issue itself - or am i wrong - 
> im confused actually :P?

Debug = no optimization. Looking at the generated assembly in a 
debug build is worthless.

You raise a valid point. In a debug build, you're probably right 
- it will need to copy the temporary to the target. With 
optimizations enabled, NRVO[0] will populate the target directly, 
resulting in roughly the equivalent of this code:

struct A {
     int field;
     static void opCall(A* p) {
         p.field = getDataFromFile("file.txt");
     }
}

A a;
A(&a);

If the function is inlined, the whole problem is of course moot. 
There are probably other optimizations that can interfere with 
what I've described.

--
   Biotronic

[0]: https://en.wikipedia.org/wiki/Return_value_optimization