Question

In C#, I use Func to replace Factories. For example:

class SqlDataFetcher    
{
    public Func<IConnection> CreateConnectionFunc;

    public void DoRead()
    {
        IConnection conn = CreateConnectionFunc(); // call the Func to retrieve a connection
    }
}

class Program    
{
    public void CreateConnection()
    {
        return new SqlConnection(); 
    }

    public void Main()
    {
        SqlDataFetcher f = new SqlDataFetcher();
        f.CreateConnectionFunc = this.CreateConnection;
        ...
    }
}

How can I simulate the code above in C++?

Answer 1

Use either std::tr1::function<IConnection*()> or boost::function<IConnection*()> as the equivalent of Func<IConnection>.

When you come to assign the function, you’ll need to bind a object and a function together;

f.CreateConnectionFunc = this.CreateConnection;

would become

f.CreateConnectionFunc = std::tr1::bind(&Program::CreateConnection,this);

(That assumes CreateConnection is not a static function – your example code doesn’t get its statics correct, so it’s difficult to tell exactly what you meant).