From: Yuval Ronen (ronen_yuval_at_[hidden])
Date: 2006-04-05 13:46:47
Yuval Ronen wrote:
> #define MY_STRUCT_AS_TUPLE(obj) const_tie(obj.x, obj.y, obj.z)
>
> bool operator<(const MyStruct &lhs, const MyStruct &rhs)
> {
> return MY_STRUCT_AS_TUPLE(lhs) < MY_STRUCT_AS_TUPLE(rhs);
> }
Nobody corrected me, but this code works just fine with the existing
boost::tie. There's no need for const_tie. I even prepared a macro to
ease the creation of comparison operators:
#define IMPLEMENT_COMPARISON_OPERATOR(TYPE, MAKE_COMPARABLE_MACRO,
OPERATOR) \
bool operator OPERATOR(const TYPE &a_lhs, const TYPE &a_rhs) \
{ \
return MAKE_COMPARABLE_MACRO(a_lhs) OPERATOR
MAKE_COMPARABLE_MACRO(a_rhs); \
}
which I can use as (if I have a struct by the name MyStruct):
#define MY_STRUCT_AS_TUPLE(obj) tie(obj.x, obj.y, obj.z)
IMPLEMENT_COMPARISON_OPERATOR(MyStruct, MY_STRUCT_AS_TUPLE, ==)
IMPLEMENT_COMPARISON_OPERATOR(MyStruct, MY_STRUCT_AS_TUPLE, <)
I think this is a very convenient way of creating comparison operators,
if anyone is interested, and maybe it will even be a good idea to add it
to the tuples documentation as "possible usages".
Hope it was useful,
Yuval