Question

In our system, we have a number of classes whose construction must happen asynchronously. We wrap the construction process in another class that derives from an IConstructor class:

class IConstructor {
    public:
        virtual void Update() = 0;
        virtual Status GetStatus() = 0;
        virtual int GetLastError() = 0;
};

There’s an issue with the design of the current system – the functions that create the IConstructor-derived classes are often doing additional work which can also fail. At that point, instead of getting a constructor which can be queried for an error, a NULL pointer is returned.

Restructuring the code to avoid this is possible, but time-consuming. In the meantime, I decided to create a constructor class which we create and return in case of error, instead of a NULL pointer:

class FailedConstructor : public IConstructor
    public:
        virtual void Update() {}
        virtual Status GetStatus() { return STATUS_ERROR; }
        virtual int GetLastError() { return m_errorCode; }
    private: int m_errorCode;
};

All of the above this the setup for a mundane question: what do I name the FailedConstructor class? In our current system, FailedConstructor would indicate “a class which constructs an instance of Failed“, not “a class which represents a failed attempt to construct another class”.

I feel like it should be named for one of the design patterns, like Proxy or Adapter, but I’m not sure which.

EDIT: I should make it clear that I’m looking for an answer that adheres to, ideally, one of the GoF design patterns, or some other well-established naming convention for things of this nature.

Answer 1

I’d name it NullConstructor in line with the null object pattern, which is the pattern you’re using. See http://en.wikipedia.org/wiki/Null_Object_pattern