Preamble:I am making a simple board game in C++, in which AI characters move around squares on the board. There are different types of squares, each inherited from an abstract class, each with different effects on the AI character. For example, some are shops where the character can buy stuff, others are workplaces where characters get money, etc.Likewise, there are different AI characters (also inherited from an abstract class), which make different kind of decisions. Some work more than others, some eat more than others, etc.The problem is that the AI character needs to know the square type in order to make a decision about what to do. At the moment checking the type using a type-name string as a member variable is the easiest solution, but it feels horribly inelegant and not very helpful when it comes to adding new types of squares and AI characters.Question: Is it bad practice to check the type of an object by asking it for an identifier which is placed into its class for this purpose? Is it bad practice to use other methods of run time type identification such as dynamic_cast and typeinfo for purposes of controlling the flow of execution?Example: Below the Square class (accessed through currentSquare() has a member function getType() which returns a string with the name of the type://Normal AI charactervoid decide() {    if(currentSquare()->getType()==HOME) {        watchTV();        sleep();    }     if(currentSquare()->getType()==WORKPLACE) {        work();    } }//Party animal AIvoid decide() {    if(currentSquare()->getType()==HOME) {        moveTo(getGameBoard()->closestBar());    }     if(currentSquare()->getType()==WORKPLACE) {        sleep();    } }
Is it bad practice to check object types with an identifying member variable?
design;c++;object oriented;data types;polymorphism
As Amon pointed out, this is a good application for the visitor pattern.  Using it, your AI classes will end up looking something like this:void decide(HomeSquare square);void decide(WorkSquare square);void decide(ShopSquare square);And your squares have an accept function that looks like:void accept(AI ai){    ai.decide(this);}That lets you use inheritance to create appropriate defaults, or force every AI to implement certain decisions.  You can create an AI that behaves exactly like another one except at home, for example, without copying a bunch of code.  The compiler will point out where you forget something, and you don't have to cast all over the place.