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PORemoving multiple inheritance
 

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  1. PORemoving multiple inheritance
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    <p>I am studying multiple inheritance, and I read that it is considered bad design.</p> <p>I created an example where multiple inheritance would be useful, and I have not found a way to rewrite it to remove multiple inheritance.<br> Furthermore, many languages do not support multiple inheritance and a new design is needed.</p> <p>The 'Animal' class implements many things that all animals do.<br> The 'AquaticAnimal' class implements everything about water.<br> The 'TerrestrialAnimal' class implements everything about animal on land. </p> <p>The 'Amphibious' class was created for animals that can do everything that 'AquaticAnimal' and 'TerrestrialAnimal' can do.<br> The application needs to use 'Amphibious' animals in the classes: Zoo, Aquarius, Plains and AmphibiousRace.</p> <p>Despite virtual inheritance, the diamond problem continues, because calling Amphibious.eat() will call Animal.eat() twice and it will lead to inconsistent state. </p> <p>It is not a real programming language, but it is like Java/C++.</p> <pre><code>class Animal{ private: Place birthplace; String name; List likesToEat; Stomach stomach; public: virtual void growl(){ ... } virtual int eat(Food food){ ... test if likes ... many operations chew() ... stomach.fill(food); } } class FlyingAnimal extends Animal { private: Wings wings; public: void fly(){ ... wings.move(); ... } } class AquaticAnimal extends Animal{ private: Flipper flipper; public: void swim(){ ... flipper.move(); ... } int eat(Food food){ int x = Animal.eat(food); ... use x flipper.nourish(food); } } class TerrestrialAnimal extends Animal{ private: Legs legs; public: void run(){ ... legs.move(); ... } int eat(Food food){ int x = Animal.eat(food); ... use x legs.nourish(food); } } class Amphibious extends AquaticAnimal, TerrestrialAnimal{ public: int eat(Food food){ AquaticAnimal.eat(food); TerrestrialAnimal.eat(food); //PROBLEM: Animal.eat() will be called twice. } } //------------------------------------------ class Zoo { public: void add/remove(Animal a); void feed(Animal a); void show(Animal a); } class Aquarius { public: void add/remove(AquaticAnimal a); } class Plains { public: void add/remove(TerrestrialAnimal a); } class HighPeaks { public: void add/remove(FlyingAnimal a); } class AmphibiousRace { public: void add/remove(Amphibious a); void enterIntoLake(Amphibious a); void exitFromLake(Amphibious a); } </code></pre>
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    1. USSquall
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    1. COThere's not even a question mark in this. Do you have a question, or is this just a brain dump?
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      1. USChris Eberle
    2. COThe question is: how to rewrite this code to remove multiple inheritance?
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