C++@子类类型转换为父类类型 static_cast(*this) to a base class create a temporary copy.

class Window {                                 // base class
public:
  virtual void onResize() { ... }              // base onResize impl
  ...
};

class SpecialWindow: public Window {          // derived class
public:
  virtual void onResize() {                   // derived onResize impl;
  static_cast<Window>(*this).onResize();      // cast *this to Window,
                                              // then call its onResize;
                                              // this doesn't work!
    ...                                       // do SpecialWindow-
  }                                           // specific stuff

  ...

};        

Effective C++:　What you might not expect is that it does not invoke that function on the current object! Instead, the cast creates a new, temporary copy of the base class part of *this, then invokes onResize on the copy!　

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Contrast:

static_cast<Window>(*this)

with:

static_cast<Window&>(*this)

One calls the copy constructor, the other does not. 

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Because you are casting actual object not a pointer or reference. It's just the same with casting double to int creates new int - not reusing the part of double.

double类型转换为int型会创建一个新的int型变量？

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上面的句子static_cast<Window>(*this).onResize();千万别改成下面这样,那样会更悲惨!

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