On Thursday, 17 October 2013 at 22:50:22 UTC, ProgrammingGhost
wrote:
How do I find out if null was passed in? As you can guess I
wasn't happy with the current behavior.
Code:
import std.stdio;
void main() {
fn([1,2]);
fn(null);
fn([]);
}
void fn(int[] v) {
writeln("-");
if(v==null)
writeln("Use default");
foreach(e; v)
writeln(e);
}
Output
-
1
2
-
Use default
-
Use default
On Thursday, 17 October 2013 at 22:51:24 UTC, ProgrammingGhost
wrote:
Sorry I misspoke. I meant to say empty array or not null passed
in. The 3rd call to fn is what I didn't like.
null implicitly converts to []. You can't distinguish them in fn.
You could add an overload for typeof(null), but that only catches
the literal null, probably not what you'd expect:
import std.stdio;
void fn(typeof(null) v) {
writeln("-");
writeln("Use default");
}
void fn(int[] v) {
writeln("-");
foreach(e; v)
writeln(e);
}
void main() {
fn([1,2]);
fn(null);
fn([]);
int[] x = null;
fn(x);
}
----
-
1
2
-
Use default
-
-
