Python 多态性的实例
谁能给我一个现实生活中的多态性实例？我的教授告诉我关于Python 多态性的实例,python,oop,polymorphism,Python,Oop,Polymorphism,谁能给我一个现实生活中的多态性实例？我的教授告诉我关于+操作符的老故事a+b=c和2+2=4，这就是多态性。我真的无法将自己与这样的定义联系起来，因为我已经在很多书中反复阅读了这个定义 我需要的是一个带有代码的真实示例，这是我可以真正联想到的 例如，这里有一个小例子，以防您想要扩展它 >>> class Person(object): def __init__(self, name): self.name = name >>> cla
+a+b=c2+2=4>>> class Person(object):
def __init__(self, name):
self.name = name
>>> class Student(Person):
def __init__(self, name, age):
super(Student, self).__init__(name)
self.age = age
查看Wikipedia示例：它在高层次上非常有用：
class Animal:
def __init__(self, name): # Constructor of the class
self.name = name
def talk(self): # Abstract method, defined by convention only
raise NotImplementedError("Subclass must implement abstract method")
class Cat(Animal):
def talk(self):
return 'Meow!'
class Dog(Animal):
def talk(self):
return 'Woof! Woof!'
animals = [Cat('Missy'),
Cat('Mr. Mistoffelees'),
Dog('Lassie')]
for animal in animals:
print animal.name + ': ' + animal.talk()
# prints the following:
#
# Missy: Meow!
# Mr. Mistoffelees: Meow!
# Lassie: Woof! Woof!
class Person(object):
def pay_bill(self):
raise NotImplementedError
class Millionare(Person):
def pay_bill(self):
print "Here you go! Keep the change!"
class GradStudent(Person):
def pay_bill(self):
print "Can I owe you ten bucks or do the dishes?"
你看，百万富翁和研究生都是人。但是当涉及到支付账单时，他们具体的“支付账单”操作是不同的。Python中一个常见的实际示例是。除了实际文件之外，还有其他几种类型，包括和，都是类似文件的。一种充当文件的方法也可以对它们起作用，因为它们支持所需的方法（例如：代码>读取< /代码>，<代码>写< /C++ >。< /P> < P>以上回答的多态性的C++示例将是：
class Animal {
public:
Animal(const std::string& name) : name_(name) {}
virtual ~Animal() {}
virtual std::string talk() = 0;
std::string name_;
};
class Dog : public Animal {
public:
virtual std::string talk() { return "woof!"; }
};
class Cat : public Animal {
public:
virtual std::string talk() { return "meow!"; }
};
void main() {
Cat c("Miffy");
Dog d("Spot");
// This shows typical inheritance and basic polymorphism, as the objects are typed by definition and cannot change types at runtime.
printf("%s says %s\n", c.name_.c_str(), c.talk().c_str());
printf("%s says %s\n", d.name_.c_str(), d.talk().c_str());
Animal* c2 = new Cat("Miffy"); // polymorph this animal pointer into a cat!
Animal* d2 = new Dog("Spot"); // or a dog!
// This shows full polymorphism as the types are only known at runtime,
// and the execution of the "talk" function has to be determined by
// the runtime type, not by the type definition, and can actually change
// depending on runtime factors (user choice, for example).
printf("%s says %s\n", c2->name_.c_str(), c2->talk().c_str());
printf("%s says %s\n", d2->name_.c_str(), d2->talk().c_str());
// This will not compile as Animal cannot be instanced with an undefined function
Animal c;
Animal* c = new Animal("amby");
// This is fine, however
Animal* a; // hasn't been polymorphed yet, so okay.
}
您是专门询问运算符多态性（也称为运算符重载）还是一般情况？一般情况下的多态性。使用
抽象未实现错误超级[Cat（），Dog（）]