There are two templated functions that overload against each other, and should
pass the unittests. But there are a few problems. Here's the example code:
T[] find(T, E)(T[] haystack, E needle)
if (is(typeof(haystack[0] != needle) == bool))
{
while (haystack.length > 0 && haystack[0] != needle) {
haystack = haystack[1 .. $];
}
return haystack;
}
T1[] find(T1, T2)(T1[] longer, T2[] shorter)
if (is(typeof(longer[0 .. 1] == shorter) : bool))
{
while (longer.length >= shorter.length) {
if (longer[0 .. shorter.length] == shorter)
break;
longer = longer[1 .. $];
}
return longer;
}
unittest {
double[] d1 = [6.0, 1.5, 2.4, 3];
float[] d2 = [1.5, 2.4];
assert(find(d1, d2) == d1[1 .. $]);
}
unittest {
double[] d = [1.5, 2.4];
assert(find(d, 1.0) == null);
assert(find(d, 1.5) == d);
string[] s = ["one", "two"];
assert(find(s, "two") == ["two"]);
}
The first unittest will fail. There is some funky issue going around here. This
small code will pass the unittest:
import std.stdio;
void main() {
}
float x = 4.0;
double y = 4.0;
unittest {
assert(x == y);
}
But this one will not:
import std.stdio;
void main() {
}
float x = 4.2;
double y = 4.2;
unittest {
assert(x == y);
}
Notice I've only changed the 0's to a different number. So, if I change the
first unittest in the original code to this:
unittest {
double[] d1 = [6.0, 1.0, 2.0, 3];
float[] d2 = [1.0, 2.0];
assert(find(d1, d2) == d1[1 .. $]);
}
It will pass. I guess this has something to do with internal representation of
floats/doubles..
The second unittest from the Example code, which I'm pasting here again for
convenience:
unittest {
double[] d = [1.5, 2.4];
assert(find(d, 1.0) == null);
assert(find(d, 1.5) == d);
string[] s = ["one", "two"];
assert(find(s, "two") == ["two"]);
}
Gives a compiler error saying that both of the overloaded templated functions
match for the call (the last assert in the unittest).
Also, Andrei, you never explained the if(is()) signature of the second
templated function. I hope to get some pointers on that. :)
