On Fri, Jan 17, 2014 at 12:51:38PM -0000, Regan Heath wrote:
> On Fri, 17 Jan 2014 05:29:05 -0000, H. S. Teoh
> <hst...@quickfur.ath.cx> wrote:
> >Now, if we modify this sentinel to instead record the location of the
> >code that first initialized it (via __FILE__ and __LINE__ default
> >parameters perhaps), then we can set it up to print out this
> >information at a convenient juncture, so that the source of the
> >uninitialized reference can be determined. *Then* perhaps it will be
> >a start of a solution to this issue. (Though it still has limitations
> >in the sense that the problem can only be caught at runtime, whereas
> >some cases of null dereference preferably should be caught at
> >compile-time.)
>
> So.. if we had a base class for all objects which obtained the file
> and line when created by assignment (from init) and threw on any
> dereference (opDispatch) that would do it, right?
[...]
If Andrei's proposal were extended so that .init can be overridden by a
member *function*, then this would work:
class NullTracker {
override typeof(this) init(string _file=__FILE__,
size_t _line = __LINE__)
{
class Impl : NullTracker {
string file;
size_t line;
this(string f, size_t l) { file=f; line=l; }
override void method1() { nullDeref(); }
override void method2() { nullDeref(); }
...
void nullDeref() {
// N.B.: puts the *source* of the
// null in the Exception.
throw new Exception(
"Null dereference",
file, line);
}
}
return new Impl(_file, _line);
}
void method1() {}
void method2() {}
...
}
T
--
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