Am 06.09.2010 21:24, schrieb Andrej Mitrovic:
Apparently I can't post to D.learn from gmail without waiting for a review?
What the..?
Anyway, I've posted this:
On a related note, I always wanted to make a template to replace the
dreaded is(typeof('delegate literal'())); calls.
For example, instead of this:
enum bool isInputRange = is(typeof(
{
R r; // can define a range object
if (r.empty) {} // can test for empty
r.popFront; // can invoke next
auto h = r.front; // can get the front of the range
}()));
We'd have a much cleaner call like so:
enum bool isInputRange = validate!(
{
R r; // can define a range object
if (r.empty) {} // can test for empty
r.popFront; // can invoke next
auto h = r.front; // can get the front of the range
});
But I haven't found a way to do it properly. If I call validate on a
type R range which doesn't feature the empty() method, then no matter
what the definition of validate is the compiler will error out because
it sees the call to r.empty() in the function literal, and 'r' doesn't
have an empty method.
You could just let your template get a string. Then
validate!q{....}
should work. It looks almost exactly the same but has a 'q'.
Maybe you could even create an template overload which gets delegate
which has always failing static assert with message "you forget the 'q'"
but I don't know if template initialization comes before semantic
analisys so I'm not sure this will work.
Mafi
