static switch/pattern matching
Lodovico Giaretta via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Sat Jun 25 05:35:39 PDT 2016
On Saturday, 25 June 2016 at 12:30:22 UTC, Lodovico Giaretta
wrote:
> If you want this to work, you need your lambdas to take the
> casted value as a parameter:
>
> void test(T)(T value) {
> int i;
> string s;
> match!(value,
> int, (val) => i = val,
> string, (val) => s = val
> );
> }
>
> And of course you need to modify match! for this to work.
Something like this:
void match(alias t, cases...)() {
static if (cases.length == 1) cases[0]();
else static if (cases.length > 2) {
static if (is(typeof(cases[0]) == bool)) {
static if (cases[0]) cases[1](t);
else match!(t, cases[2 .. $]);
}
else static if (is(typeof(t) == cases[0])) cases[1](t);
else match!(t, cases[2 .. $]);
}
}
void test(T)(T value) {
int i;
string s;
match!(value,
int, (val) => i = val,
string, (val) => s = val
);
}
void main()
{
test(1);
test("A string");
}
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