使用私有函数覆盖公共虚函数？ [英] Override public virtual Functions with private Functions?
问题描述
Hello All
我有一个名为Action_Request的基类，以及一组对应于不同种类的Action_Request的类
，每个类都继承<来自Action_Request的
。例如： -
class Add_Molecule_Req：public Action_Request {
// ......
};
我使用虚拟函数通过
Action_Requests的公共接口以多态方式操作各种派生类。
目前最重要的功能是派生类（包括
析构函数，它会覆盖Action_Request的虚拟析构函数），
声明公开。
我的程序编译，如果我将它们设为私有，并且这样做似乎
的优点是必须始终调用这些函数
通过Action_Request的公共接口进行多态化，这就是我想要的b $ b。
我的问题是： -
i）覆盖公共虚拟功能私人功能好
练习？
ii）有没有缺点？
Chris Gordon-Smith
<一个rel =nofollow href =http://www.simsoup.infotarget =_ blank> www.simsoup.info
Hello All
I have a base class called Action_Request, and a set of classes
corresponding to different kinds of Action_Request, each of which inherits
from Action_Request. Eg:-
class Add_Molecule_Req: public Action_Request{
// ......
};
I manipulate the various derived classes polymorphically through
Action_Requests''s public interface, using its virtual functions.
Currently the overriding functions in the derived classes (including the
destructor, which overrides Action_Request''s virtual destructor), are
declared public.
My program compiles if I make them private, and doing this would seem to
have the advantage that these functions must then always be invoked
polymorphically through Action_Request''s public interface, which is what I
want.
My questions are:-
i) Is overriding public virtual functions with private functions good
practice?
ii) Are there any disadvantages?
Chris Gordon-Smith
www.simsoup.info
推荐答案
Chris Gordon-Smith< us ********* @ my.homepagewrote：
Chris Gordon-Smith <us*********@my.homepagewrote:
我有一个名为Action_Request的基类，以及一组类
对应不同类型的Action_Request，每个Action_Request都从Action_Request继承
。例如： -
class Add_Molecule_Req：public Action_Request {
// ......
};
我使用虚拟函数通过
Action_Requests的公共接口以多态方式操作各种派生类。
目前最重要的功能是派生类（包括
析构函数，它会覆盖Action_Request的虚拟析构函数），
声明公开。
我的程序编译，如果我将它们设为私有，并且这样做似乎
的优点是必须始终调用这些函数
通过Action_Request的公共接口进行多态化，这就是我想要的b $ b。
我的问题是： -
i）覆盖公共虚拟功能私人功能好
练习？
ii）有任何缺点吗？
I have a base class called Action_Request, and a set of classes
corresponding to different kinds of Action_Request, each of which inherits
from Action_Request. Eg:-
class Add_Molecule_Req: public Action_Request{
// ......
};
I manipulate the various derived classes polymorphically through
Action_Requests''s public interface, using its virtual functions.
Currently the overriding functions in the derived classes (including the
destructor, which overrides Action_Request''s virtual destructor), are
declared public.
My program compiles if I make them private, and doing this would seem to
have the advantage that these functions must then always be invoked
polymorphically through Action_Request''s public interface, which is what I
want.
My questions are:-
i) Is overriding public virtual functions with private functions good
practice?
ii) Are there any disadvantages?
我倾向于遵循指南，如果可以，请将其设为私有，公开，如果你必须使用
。我认为这样的代码是良好实践。
唯一的缺点是，某个具有某些
ActionRequest子类的对象将不得不向上 - 投射对象。
I tend to follow the guideline, "make it private if you can, public if
you must." I consider such code "good practice".
The only disadvantage is that someone with a object of some
ActionRequest sub-class will have to up-cast the object.
Chris Gordon-Smith写道：
Chris Gordon-Smith wrote:
我的问题是： -
i）用私人功能覆盖公共虚拟功能好
练习？
ii）有缺点吗？
My questions are:-
i) Is overriding public virtual functions with private functions good
practice?
ii) Are there any disadvantages?
一般来说，你应该将接口（公共API，基类
提供）与可配置性（覆盖功能）分开。这也是
称为模板方法模式，这里有详细描述：
http://www.gotw.ca/publications/mill18.htm
-
Dizzy
In general you should separate interface (the public API the base class
provides) from configurability (the overriding feature). This is also
called the Template Method Pattern and is described in detail here:
http://www.gotw.ca/publications/mill18.htm
--
Dizzy
Daniel T.写道：
Daniel T. wrote:
Chris Gordon-Smith< us ** *******@my.homepagewrote：
Chris Gordon-Smith <us*********@my.homepagewrote:
>我有一个名为Action_Request的基类，以及一组对应不同的类
各种Action_Request，每个都继承自Action_Request。例如： -
类Add_Molecule_Req：public Action_Request {
// ......
};
我以多态方式操纵各种派生类通过Action_Requests的公共接口，使用其虚函数。
目前派生类中的重写函数（包括覆盖Action_Request的虚拟析构函数的
析构函数）是<声明公开。
我的程序编译如果我将它们设为私有，并且这样做似乎具有以下优点：必须始终通过多态来调用这些函数Action_Request的公共界面，这就是我想要的。
我的问题是： -
i）覆盖公共虚拟功能与私人功能良好<实践？
ii）有任何缺点吗？
>I have a base class called Action_Request, and a set of classes
corresponding to different kinds of Action_Request, each of which
inherits from Action_Request. Eg:-
class Add_Molecule_Req: public Action_Request{
// ......
};
I manipulate the various derived classes polymorphically through
Action_Requests''s public interface, using its virtual functions.
Currently the overriding functions in the derived classes (including the
destructor, which overrides Action_Request''s virtual destructor), are
declared public.
My program compiles if I make them private, and doing this would seem to
have the advantage that these functions must then always be invoked
polymorphically through Action_Request''s public interface, which is what
I want.
My questions are:-
i) Is overriding public virtual functions with private functions good
practice?
ii) Are there any disadvantages?
我倾向于遵循指南，如果可以，请将其设为私有，公开，如果你必须使用
。我认为这样的代码是良好做法。
I tend to follow the guideline, "make it private if you can, public if
you must." I consider such code "good practice".
对我来说听起来很明智。我没有意识到（因为我没有真正想过它），派生类中的私有方法可以覆盖基础中的公共方法。
Sounds sensible to me. What I hadn''t appreciated (because I hadn''t really
thought about it), is that private methods in derived class can override
public methods in the base.
唯一的缺点是，某个具有某些对象
ActionRequest子类的对象必须向上转换该对象。
The only disadvantage is that someone with a object of some
ActionRequest sub-class will have to up-cast the object.
在我的情况下，这不是一个问题，因为操纵只需要通过基地进行
。如果我尝试通过派生的
类指针进行操作，我将收到编译器错误。上传是可能的，但
将违背我的基本设计原则。
Chris Gordon-Smith
www.simsoup.info
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