digitalmars.D.bugs - max(byte, byte)
Is this a bug?
----------------------------------------------------------------
$ cat max.d
import std.math2;
int main()
{
byte a, b;
return max(a,b);
}
----------------------------------------------------------------
$ dmd max.d
max.d(6): function std.math2.max called with argument types:
(byte,byte)
matches both:
std.math2.max(int,int)
and:
std.math2.max(real,real)
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There's no partial ordering on type? e.g byte < short < int < real, so the
nearest one should be picked up?
BTW, the implementation in src/phobos/std/math2.d
is ugly:
int max(int a, int b) ...
long max(long a, long b) ...
real max(real a, real b) ...
Why can't D's template be use here?
Mar 26 2005
pragma <pragma_member pathlink.com> In article <d25ana$163u$1 digitaldaemon.com>, bug d.com says...Is this a bug? ---------------------------------------------------------------- $ cat max.d import std.math2; int main() { byte a, b; return max(a,b); } ---------------------------------------------------------------- $ dmd max.d max.d(6): function std.math2.max called with argument types: (byte,byte) matches both: std.math2.max(int,int) and: std.math2.max(real,real) ---------------------------------------------------------------- There's no partial ordering on type? e.g byte < short < int < real, so the nearest one should be picked up? BTW, the implementation in src/phobos/std/math2.d is ugly: int max(int a, int b) ... long max(long a, long b) ... real max(real a, real b) ... Why can't D's template be use here?D's type-matching for function signatures is dead-simple. Either it finds an exact match, or it matches any (and all) methods with a valid implicit cast to the parameter type. In this case, byte can be implicitly cast to int *or* real, so it's complaining that your code is ambiguous. You wouldn't want to have some implicit cast ordering to resolve these matters, as that would lead to hard to debug code; in your example above, how would you know which max() function is being called?. IMO, we all want fewer such rules, rather than more. Anyway, the solution here is simple: use a shim function to remove the ambiguity.byte max(byte a, byte b){ return cast(byte)max(cast(int)a,cast(int)b); }.. or use the casts directly in your code. - EricAnderton at yahoo
Mar 28 2005