Re: mutable keyword

[Namespace via Digitalmars-d-learn]

On Thursday, 19 May 2016 at 23:21:14 UTC, Jonathan M Davis wrote:

On Thursday, May 19, 2016 20:44:54 ciechowoj via Digitalmars-d-learn wrote:

Is there D equivalent of C++'s mutable keyword? Like the one that allows to modify a field of struct from constant method. Or some alternative solution?

No. D's const and immutable provide no backdoors.

But you can cheat:
----
int* _id;

struct A
{
        int id = 0;
        
        this(int id)
        {
                this.id = id;
                _id = &this.id;
        }
        
        void change() const
        {
                (*_id)++;
        }
}

void main() {
        import std.stdio;
        
        A a = A(42);
        a.change();
        
        writeln(a.id);
}
----