您可以重載操作符的地址以返回句柄並聲明兩個句柄(沒有定義)的比較。這會導致鏈接器錯誤。
#include <iostream>
class Op;
class Handle {
Op *pri_;
public:
explicit Handle(Op *o) : pri_(o) {}
Op *operator->() const { return pri_; }
Op &operator*() const { return *pri_; }
};
// force compile time errors on comparison operators
bool operator==(const Handle &, const Handle &) = delete;
bool operator!=(const Handle &, const Handle &) = delete;
bool operator>=(const Handle &, const Handle &) = delete;
bool operator<=(const Handle &, const Handle &) = delete;
bool operator<(const Handle &, const Handle &) = delete;
bool operator>(const Handle &, const Handle &) = delete;
class Op {
int foo_;
public:
explicit Op(int i) : foo_(i) { }
Handle operator&() { return Handle(this); };
void touch() const { std::cout << "foobar"; }
};
int main(int argc, char **argv) {
Op i{10};
Op j{20};
auto c = &j; // works
c->touch(); // works
(*c).touch(); // works
if (&j == &i) {
/* will not compile */
}
}
注意:
你必須履行Handle
的random_access_iterator
要求!
Op i{10}
Handle ref = &i;
ref++; ref--; ++ref; --ref; ref = ref + 10; ref = ref - 10; // should all work.
顯示代碼或至少是您實際嘗試實現的最小工作簡化示例。 – Alex 2014-08-28 13:03:44