On 6/28/17 1:52 AM, Dmitry Solomennikov wrote:
On Wednesday, 28 June 2017 at 05:01:17 UTC, Eugene Wissner wrote:
On Wednesday, 28 June 2017 at 04:41:25 UTC, Dmitry Solomennikov wrote:
Probably if you have serialized data, you convert strings to other
types, so it may be possible to perfom if-checks:
if (myDataIsStringAndDouble(data))
{
auto var = new Some!(Pair!(string, double))(new Pair!(string,
double)("df", 5.0));
}
else if (myDataIsStringAndInt(data))
{
auto var = new Some!(Pair!(string, int))(new Pair!(string,
int)("df", 5));
}
It is possible, but it is not a general solution. I've posted couple of
sample classes, but there are more complicated cases, of course, and it
well be combinatorial explosion here.
I got the Variant idea, I'll give it a try.
From other point of view, is there a reflection, say
auto i = newInstance("Pair!(int, string)(10, \"asdf\")"),
No, because the class itself doesn't eixst until you instantiate it.
Certainly if you want to write out all the possible instantiations, it's
possible, via the mechanisms already specified above. What I would do is
create a newInstance *template* that takes a string and generates a
function that would build it from that string. Then you can feed a
sample file that contains all the possible instantiations to it at
*compile time* (via import strings), and then you can automatically
build the code that would be able to parse it. Finally, send the real
file at runtime.
something like in Java?
It's important to realize that Java's generics are completely different
than D's templates. They are a compile-time wrapping around a runtime
construct. Of course, it's possible to mimic Java, but you won't get
templates out of it, more like Variant holders.
-Steve
