Start with:
struct X {
char c[];
}
Assume you want value semantics - postblit provides this
capability. It appears with 2.061 'this(this) const' is now
supported. Previously, only 'this(this)' was recognized (i.e.
called) when expected. To get value semantics a developer must
choose between these two and for this case the goal is to ensure
'c = c.dup;' so value semantics are preserved.
Case 1: Go with 'this(this) { c = c.dup; }'. This works just fine
except for the case where you want a const(X) as a member of some
other class. For example: struct Y { const(X) x; }.
Case 2: Go with 'this(this) const { c = c.dup; }'. This is not
possible because you can not change 'c' since the function is
const. Maxim Fomin pointed out a workaround.
struct X {
char c[];
void _postblit_() { c = c.dup; }
this(this) const {
void delegate() dg = &_postblit_;
dg();
}
}
This workaround succeeds, but, based on this thread
(http://forum.dlang.org/thread/[email protected])
I don't know if it is a bug or not. If it is not a bug, I would
doubt it is the prescribed approach for doing this?
So, the question is:
What is the best *current* way to code X to achieve struct Y {
const(X) x; } and what is the long run solution to this(this)?
Thanks,
Dan
