I'm trying to figure out how to do something like this:
for_each(c.begin(), c.end(), cout << _1.member << "\n");
which is obviously wrong, but hopefully you know what I mean...
Experimenting with ways of accessing members inside a lambda, I wrote
the following:
#include <iostream>
#include
#include <vector>
using namespace std;
using namespace boost;
using namespace lambda;
struct XX {
XX(int a, int b) { a_ = a; b_ = b; }
int a_;
int b_;
};
int main() {
XX xx(5, 6);
XX *xxp = &xx;
cout << "These should all be equivalent:\n";
cout << xxp ->* &XX::a_ << endl;
cout << (_1 ->* &XX::a_)(xxp) << endl;
//cout << (_1 ->* &XX::a_)(&xx) << endl; // Doesn't compile!
cout << (&_1 ->* &XX::a_)(xx) << endl;
cout << "Now, let's try with the vector:\n";
vector<XX> xxVec;
xxVec.push_back(XX(3, 4));
cout << (&_1 ->* &XX::a_)(xxVec[0]) << endl;
//cout << (_1 ->* &XX::a_)(&xxVec[0]) << endl; // Doesn't compile!
cout << (_1 ->* &XX::a_)(xxp = &xxVec[0]) << endl; // Now it
compiles...
//cout << (_1 ->* &XX::a_)(xxVec.begin()) << endl; //
Doesn't compile!
//cout << (_1 ->* &XX::a_)(&*xxVec.begin()) << endl; //
Still not...
cout << (_1 ->* &XX::a_)(xxp = &*xxVec.begin()) << endl; // Now
it compiles...
exit(0);
}
I'm mystified by why some of these lines don't compile (gcc 3.2.2). Can
anyone explain it? The compiler generates some horrific error messages
-- I haven't tried to pick through them yet...
- Chuck
