On 18/01/12 17:07, Timon Gehr wrote:
On 01/18/2012 04:57 PM, Timon Gehr wrote:
On 01/18/2012 02:32 PM, Jerome BENOIT wrote:
On 18/01/12 04:36, Jonathan M Davis wrote:
On Wednesday, January 18, 2012 02:33:25 Jerome BENOIT wrote:
And I cannot figure why :-(
http://d.puremagic.com/issues/show_bug.cgi?id=1528
As a workaround, templatize the last function by changing its
signature to
int[] find()(int[] longer, int[] shorter)
actually it does not work either: gdmd gives an other error message now.
------------------------------------------------------------------------
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;
}
TL[] find(TL, TS)(TL[] longer, TS[] 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;
}
int[] find()(int[] longer, int[] shorter) {
while (longer.length >= shorter.length) {
if (longer[0 .. shorter.length] == shorter) break;
longer=longer[1 .. $];
}
return longer;
}
unittest {
// Test the introduced overloads
long[] a1 = [ 6, 1, 2, 3 ];
long[] a2 = [ 1 , 2 ];
int[] b1 = [ 6, 1, 2, 3 ];
int[] b2 = [ 1 , 2 ];
assert(find(a1, a2) == a1[1 .. $]);
assert(find(a1, b2) == a1[1 .. $]);
assert(find(b1, b2) == b1[1 .. $]);
}
void main() {}
------------------------------------------------------------------------
The message is now:
searching_05.d:34: Error: template searching_05.find(T,E) if
(is(typeof(haystack[0] != needle) == bool)) find(T,E) if
(is(typeof(haystack[0] != needle) == bool)) matches more than one
template declaration, searching_05.d(9):find(TL,TS) if
(is(typeof(longer[0..1] == shorter) : bool)) and
searching_05.d(18):find()
Is partial ordering really supported ?
Yes it is, and your code snippet indeed compiles on my machine. Are you
maybe using an outdated version of the compiler?
Nevermind, I forgot to pass the -unittest switch. It indeed gives that error.
The reason it still does not compile is that the workaround proposed by
Jonathan has slightly different semantics than it would have if the compiler
already supported overloading of functions against function templates.
If exactly one of two equally good matched functions is a templated one, the
other one is chosen.
So the D code in my first post may work and thus the workaround is not
necessary.
For information, I use gdc on a Debian Testing box.
Now that you have templated the second function, both are an equally good
match and both are templated.
If you change the last signature to
int[] find(TL:int[], TS:int[])(TL longer, TS shorter)
It will compile. However, if TL or TS are user-defined types with an alias this
of type int[], the semantics are still different. I think this bug needs
special attention.
