Question

有这段代码：

#include <iostream>
class SomeClass
{
  int someInteger;
  float someFloat;
public:
  SomeClass(int someInteger_)
  {
    // do something for int
    std::cout << "Int constructor\n";
  }
  SomeClass(float someFloat_)
  {
    // do something for float
    std::cout << "Float constructor\n";
  }
};

int main()
{
  SomeClass a(2);
  SomeClass b(2.0f);
  return 0;
}

当传递构造函数的float或int参数时，SomeClass类的对象会被不同地创建。 Python中有类似的类：

class SomeClass:
    someInteger = 0
    someFloat = 0.0
    def __init__(self, value):
        # I want to do different things when int or float is passed
        print value

a = SomeClass(2)
b = SomeClass(2.0)

一般问题是 - 如何使函数行为依赖于传递参数的类型？

Answer 1

使用isinstance：

>>> isinstance(1, int)
True
>>> isinstance(1, float)
False
>>> isinstance(1.1, float)
True
>>> isinstance(1.1, int)
False

或者你的构造函数：

def __init__(self, value):
    if isinstance(value, int):
        # int constructor
    elif isinstance(value, float):
        # float constructor
    else:
        raise TypeError, 'Unexpected type'

从C ++角度重载Python中的构造函数

1 个答案: