class Car {
    // ...
    private:
        Engine engine;
        Hood hood;
};

// The car is *composed* of an engine and a hood. Hence, composition. You are
// also bringing together (i.e. *aggregating*) an engine and hood into a car.

interface Car {
    public Engine getEngine();
    public Hood getHood();
    public void drive();
}
// In the above, the fact that a car has these building blocks
// is a part of its interface (the abstraction).

class HondaCivic2010 implements Car {
    public void drive(){ getEngine().drive(); }
    // ...
}
// In the above, composition/delegation is an implementation
// strategy for providing the drive functionality.

class GoodCharacter;
class BadCharacter;
class Mage;
class Rogue;
class GoodMage : public GoodCharacter, Mage;
class BadMage : public BadCharacter, Mage;
class GoodRogue : public GoodCharacter, Rogue;
class BadRogue : public BadCharacter, Rogue;

class Personality;
 class GoodPersonality : public Personality;
 class BadPersonality : public Personality;

 class CharacterClass;
 class Mage : public CharacterClass;
 class Rogue : public CharacterClass;

 class Character {
    public:
        // ...
    private:
        CharacterClass character_class;
        Personality personality;
 };
 // A character has both a character class and a personality.
 // This is a perfect example of the bridge pattern, and we've
 // reduced MxN classes into a mere M+N classes, and we've
 // arguably made the system even more flexible than before.

* you want to avoid a permanent binding between an abstraction and its implementation. This might be the case, for example, when the implementation must be selected or switched at run-time.

* both the abstractions and their implementations should be extensible by subclassing. In this case, the Bridge pattern lets you combine the different abstractions and implementations and extend them independently.

* changes in the implementation of an abstraction should have no impact on clients; that is, their code should not have to be recompiled.

* (C++) you want to hide the implementation of an abstraction completely from clients. In C++ the representation of a class is visible in the class interface.

* you have a proliferation of classes as shown earlier in the first Motivation diagram. Such a class hierarchy indicates the need for splitting an object into two parts. Rumbaugh uses the term "nested generalizations" [RBP+91] to refer to such class hierarchies.

* you want to share an implementation among multiple objects (perhaps using reference counting), and this fact should be hidden from the client. A simple example is Coplien's String class [Cop92], in which multiple objects can share the same string representation (StringRep).

interface ISpeak
{
    void Speak();
}

class DogSpeak : ISpeak
{
    public void Speak()
    {
        Console.WriteLine("Dog Barks");
    }
}
class CatSpeak : ISpeak
{
    public void Speak()
    {
        Console.WriteLine("Cat Meows");
    }
}

abstract class AnimalBridge
{
    protected ISpeak Speech;

    protected AnimalBridge(ISpeak speech)
    {
        this.Speech = speech;
    }

    public abstract void Speak();
}
class Dog : AnimalBridge
{
    public Dog(ISpeak dogSpeak)
        : base(dogSpeak)
    {

    }
    public override void Speak()
    {
        Speech.Speak();
    }
}

class Cat : AnimalBridge
{
    public Cat(ISpeak catSpeak)
        : base(catSpeak)
    {

    }
    public override void Speak()
    {
        Speech.Speak();
    }
}