Re: bind2nd, mem_fun, and references
* Noah Roberts:
#include <vector>
#include <algorithm>
#include <functional>
class X
{
int x;
public:
X(int i) : x(i) {}
bool eq(const X & other) const { return x == other.x; }
};
int main(int argc, char* argv[])
{
std::vector<X> xes(10);
X x(10);
std::vector<X>::iterator it = std::find_if(xes.begin(), xes.end(),
std::bind2nd(std::mem_fun(&X::eq), x));
return 0;
}
Compilation result:
1>c:\program files\microsoft visual studio 8\vc\include\functional(312)
: error C2529: '_Right' : reference to reference is illegal
binder2nd(const _Fn2& _Func,
const typename _Fn2::second_argument_type& _Right)
: op(_Func), value(_Right)
{ // construct from functor and right operand
}
This would follow...
So, what is the correct and portable way to do what I want or is it
just not possible?
One way could be to use to Boost binders (don't know if that works, but
probably, else I would probably have remembered). Another way is to
define a free comparision function. A third, slight adjustment:
#include <vector>
#include <algorithm>
#include <functional>
class X
{
int x;
public:
X(int i) : x(i) {}
bool operator==(const X & other) const { return x == other.x; }
};
int main()
{
std::vector<X> xes(10, X(0));
X x(10);
std::vector<X>::iterator it = std::find_if(
xes.begin(),
xes.end(),
std::bind2nd(std::equal_to<X>(), x)
);
}
--
A: Because it messes up the order in which people normally read text.
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A: Top-posting.
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