Question

I have the following data container:

struct Node
{
    explicit Node(const std::vector<Data>& _data, const Value& _value): data(_data), value(_value)
    {
    }

    const std::vector<Data> data;
    const Value value;
};

I wish to write a mock along these lines:

class MockVisitor: public IVisitor
{
public:
    virtual void operator()(const Node& _node)
    {
        node = _node;
    }

    Node node;
};

However, I’m getting the error:

error C2582: 'operator =' function is unavailable in 'Node'. 

I’m presuming this is because I can only assign to a const Node. Is there anyway for my to cast away this error? Remember this is only a mock class. I’m simply trying to record the value passed into operator()() so I can check it in my unit test.

Answer 1

Since the member variables data and value are declared as constant, the operator= is deleted. This is the reason you can not use it, hence the compilation error.

This should work :

class MockVisitor: public IVisitor
{
public:
    virtual void operator()(const Node& _node)
    {
        node.reset( new Node( _node ) );
    }

    std::unique_ptr< Node > node;
};