On Wednesday, 5 September 2012 at 11:01:50 UTC, Artur Skawina
wrote:
On 09/04/12 20:19, Era Scarecrow wrote:
I ask you, how do you check if it's a null pointer? &s?
Yes, obviously. If you need to do that manually.
int getx(ref S s)
//How does this make sense?? it looks wrong and is misleading
in {assert(&s); }
body {return s.x); }
It looks correct and is perfectly obvious. But see below - you
don't need to do this manually - the compiler does it for you
when calling methods and could handle the UFCS case too.
I've been thinking about this; It would definitely be the wrong
thing to do. The assert would _Always_ succeed. The address you
get would be of the pointer/reference for the stack (the pointer
variable exists, where it points to isn't so much the case), so
it would be the same as comparing it to this...
int getx(S* s)
in {assert(&s);} //always true, and always wrong.
As I mentioned, it's wrong and is misleading. You'd have to work
around the system to get the check correct; and even then if the
compile decides to do something different you can only have it
implementation dependent.
int getx(ref S s)
in {
S *ptr = cast(S*) s;
assert(ptr);
}
I'm not even sure this would even work (it's undefined
afterall). I hope I never have to start adding such odd looking
checks, else I would throw out ref and use pointers instead; At
least with them the checks are straight-forward in comparison.
