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copied!<p>You can refactor this:</p> <pre><code>if ( otherAObj.IsActive() ) { //do something with aObj } </code></pre> <p>out into a doSomething() function</p> <pre><code>public class A{ virtual bool isActive(){ return false; } virtual bool isPending(){ return false; } virtual void doSomething() { if(true == isActive()) { ... if(false == isPending()) { ... } ... } }; } public class A_State_Active : A { bool isActive(){ return true; } } public class A_State_Pending : A { bool isPending(){ return true; } void doSomething() { throw new InvalidOperationException("Don't be messing"); } } </code></pre> <p>Or even make the base version of doSomething pure virtual to force the users to implement a state specific version.</p> <p>However you should not implement anything in your subclasses that is based on the state of a different object. IMO you should use a manager type object in that case. If really want to do it that way you should just pass a reference to the other objects to the <code>doSomething()</code> function and modify the runtime behaviour based on the return values of the passed object's state (query using the "isActive"/"isPending" API).</p> <p>Other option is to do away with inheritance and favour composition. Have <code>A</code> be one class which holds a reference to an <code>A_State</code> class. You then subclass <code>A_State</code>. </p> <pre><code>class A { //public functions ... const A_State* getState(){ return m_poMyState; } void setState(const A_State const * aStateObj ){ m_poMyState = aStateObj; } } </code></pre>

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