On Sunday, 28 April 2013 at 17:02:57 UTC, bearophile wrote:
Idan Arye:
When you use `std.typecons.Nullable` with a type that already
accept `null` values, you get two types of nulls - the
`Nullable`'s null state the the regular type's `null`:
Nullable!string a;
writeln(a.isNull()); //prints "true"
a = null;
writeln(a.isNull()); //prints "false"
Originally D dynamic arrays were almost conflated with regular
pointers (they were seen as fat pointers). This was recently
partially fixed (so assigning a pointer to a dynamic array is
now forbidden), but accepting "null" for their empty literal is
one left part of that original suboptimal design.
Time ago I have proposed to forbid "null" as literal for an
empty dynamic array literal, an empty associative literal, or
an empty string, and to accept only [] "" [:] (D already has
the first two literals and the third looks natural).
See also:
http://d.puremagic.com/issues/show_bug.cgi?id=3889
http://d.puremagic.com/issues/show_bug.cgi?id=5788
http://d.puremagic.com/issues/show_bug.cgi?id=7227
Bye,
bearophile
I used `Nullable!string` for the example, but it could just as
easily be `Nullable!Object` or `Nullable!(int*)`.
