#include <string>
#include "boost/variant/variant.hpp"
#include "boost/variant/apply_visitor.hpp"
using namespace std;
class Base
{
public:
Base(){}
~Base(){}
void AddField(int tag, int value){std::cout << "Base::AddField " << tag << ", " << value << std::endl;}
void AddField(int tag, string value){std::cout << "Base::AddField " << tag << ", " << value << std::endl;}
};
class A : public Base
{
public:
A(){}
~A(){}
};
class B : public Base
{
public:
B(){}
~B(){}
};
class foo_visitor
: public boost::static_visitor<>
{
public:
foo_visitor(int tag){mTag = tag;}
template <typename T>
void operator()(T &a, int &v) const {
a->AddField(mTag, v);
}
private:
int mTag;
};
int main(int argc, char **argv)
{
typedef boost::variant<A*,B*> AB;
AB ab = new A();
int tag = 1;
int v = 2;
boost::apply_visitor(foo_visitor(tag), ab, v);
return 0;
}
我遇到这个编译错误:
apply_visitor_unary.hpp:60:43: error: request for member ‘apply_visitor’ in ‘visitable’, which is of non-class type ‘int’
我的代码有什么问题?
最佳答案
int
实际上不是 variant
。
Overloads accepting two operands invoke the binary function call operator of the given visitor on the content of the given variant operands.
http://www.boost.org/doc/libs/1_52_0/doc/html/boost/apply_visitor.html
关于c++ - 为什么这个二进制 apply_visitor 不工作?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15270512/