Item 7: declare Destructors (destructor) as virtual in polymorphic base classes (polymorphism base class)
By Scott Meyers
Translator: fatalerror99 (itepub's nirvana)
Release: http://blog.csdn.net/fatalerror99/
There are many ways to get the time, so
Polymorphism is a basic attribute of object-oriented, including static polymorphism (compile phase) and dynamic polymorphism (runtime phase). Static polymorphism mainly refers to the polymorphism of different function parameters, which is a
From the syntax above, it is possible for destructors to throw exceptions, and C + + does not prevent destructors from throwing exceptions, but C + + does not recommend this practice, and it is dangerous to throw exceptions from
C ++ inherits the calling sequence and virtual destructor of the destructor in the destructor.
First, let's talk about the constructor. We all know that the constructor can call member variables, and the Child class in inheritance is to turn the
Document directory
The constructor cannot be declared as a virtual function. The Destructor can be declared as a virtual function, and sometimes it must be declared as a virtual function.
The constructor cannot be declared as a virtual function.
In C ++, virtual constructor cannot be declared, but virtual destructor can be declared. Polymorphism means that different objects have different behavior characteristics for the same message. As the basis of Runtime polymorphism, virtual functions
Reference: http://www.weixueyuan.net/view/6373.htmlSummarize:A constructor cannot be declared as a virtual function, and a destructor can be declared as a virtual function.After the destructor of the base class is declared as a virtual function, the
In the previous article, we introduced why we should avoid writing copy constructors and value assignment operators. Today we will discuss why we should avoid writing code in the destructor. That is, leave the Destructor empty.
For example:
virtual
turn from: http://blog.csdn.net/liuning800203/article/details/6455226
Releasing resources with destructors
Destructors are used to deconstruct instances of classes.
1 The destructor cannot be defined in the structure. Destructors can only be used
Declare the destructor of the polymorphism base class as a virtual function.
Now we want to consider a timer problem. First we create a base class named timekeeper, and then create various derived classes based on it, so that we can use different
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