继承自std :: vector？ [英] Inheriting from std::vector?

问题描述

一位同事有这样的代码：


class CMyObject {

//一群会员功能

}


类CMyObjectList：public std :: vector< CMyObject>

{

//一堆成员函数

}


我需要继承他的对象和列表的功能以及添加

我自己的一些：


class CMyPersonalObject：public CMyObject

{

//更多东西

}


类CMyPersonalObjectList：public CMyObjectList

{

//更多东西

}


但是如果我将CMyPersonalObjectList传递给一个函数，然后尝试将CMyPersonalObject分配给该类型的局部变量，我得到一个编译器

错误告诉我我无法将CMyObject转换为CMyPersonalObject ...

编译器认为我传入的列表是由父对象组成的。


发生了什么事，我该如何解决？


谢谢，

B

Hi,

A colleague has some code like this:

class CMyObject {
// Bunch of Member functions
}

class CMyObjectList: public std::vector<CMyObject>
{
// Bunch of member functions
}

I need to inherit the functionality of his object and list as well as add
some of my own:

class CMyPersonalObject: public CMyObject
{
// More stuff
}

class CMyPersonalObjectList: public CMyObjectList
{
// More stuff
}

But if I pass in CMyPersonalObjectList to a function, and then try to assign
the CMyPersonalObject to a local variable of that type, I get a compiler
error telling me that I cannot convert CMyObject to CMyPersonalObject... the
compiler thinks the list I passed in is made of the parent objects.

What is going on and how do I fix it?

Thanks,
B

推荐答案

BCC写道：

BCC wrote:

但是如果我将CMyPersonalObjectList传递给一个函数，然后尝试将CMyPersonalObject分配给这个类型的局部变量，我得到一个编译器
错误告诉我我无法将CMyObject转换为CMyPersonalObject ...
编译器认为我传入的列表是由父对象组成的。

发生了什么以及如何解决？

But if I pass in CMyPersonalObjectList to a function, and then try to assign
the CMyPersonalObject to a local variable of that type, I get a compiler
error telling me that I cannot convert CMyObject to CMyPersonalObject... the
compiler thinks the list I passed in is made of the parent objects.

What is going on and how do I fix it?

需要查看分配的代码。

但是，由于std :: vector没有虚拟析构函数，因此
不应该被用作基类。这不是你实际问题的原因。

Would need to see the code where the assignment is made.
However, as std::vector doesn''t have a virtual destructor it
shouldn''t really be being used as a base class. That isn''t
your actual problem though.

2003年10月23日星期四23:47:14 GMT， " BCC" <峰; br *** @ akanta.com>写道：

On Thu, 23 Oct 2003 23:47:14 GMT, "BCC" <br***@akanta.com> wrote:

一位同事有这样的代码：

类CMyObject {
//一群成员函数
}


缺少分号。

类CMyObjectList：public std :: vector< CMyObject>
{
//一串成员函数}


同上。


如果没有进一步的信息，这种继承有点可疑。


我可以从std :: string继承，但不是std :: vector。


我需要继承他的对象和列表的功能以及添加
类CMyPersonalObject：public CMyObject
{
//更多东西
}
类CMyPersonalObjectList：public CMyObjectList
{
//更多东西
}

但是如果我将CMyPersonalObjectList传递给一个函数，然后尝试将CMyPersonalObject分配给一个函数这种类型的局部变量，


没有重新CMyPersonalObjectList和CMyPersonalObject之间的关系

你所展示的内容，所以上面似乎毫无意义。

我得到一个编译器
错误告诉我我无法将CMyObject转换为CMyPersonalObject ...


编译器是对的，除非你提供转换，否则你不能这样做。

编译器认为我传入的列表是由父对象。


你到底在哪里得到那个荒谬的想法？编者不会想。

发生什么事情


见例如< url：http：//news.google.com/>。

我该如何解决？

A colleague has some code like this:

class CMyObject {
// Bunch of Member functions
}
Missing semicolon.
class CMyObjectList: public std::vector<CMyObject>
{
// Bunch of member functions
}
Ditto.

Without further information this inheritance is a little suspicious.

I can thing of good reasons to inherit from std::string, but not std::vector.

I need to inherit the functionality of his object and list as well as add
some of my own:

class CMyPersonalObject: public CMyObject
{
// More stuff
}

class CMyPersonalObjectList: public CMyObjectList
{
// More stuff
}

But if I pass in CMyPersonalObjectList to a function, and then try to assign
the CMyPersonalObject to a local variable of that type,
There is no relationship between CMyPersonalObjectList and CMyPersonalObject
in what you have shown, so the above seems meaningless.
I get a compiler
error telling me that I cannot convert CMyObject to CMyPersonalObject...
The compiler is right, you cannot do that unless you provide a conversion.
the compiler thinks the list I passed in is made of the parent objects.
Where on earth did you get that absurd idea? Compilers don''t think.
What is going on
See e.g. <url: http://news.google.com/>.
and how do I fix it?

也许关注Michael Moore的建议？

Perhaps follow the advice of Michael Moore?

2003年10月23日星期四23:47:14 GMT，BCC< br *** @ akanta.com>写道：

On Thu, 23 Oct 2003 23:47:14 GMT, BCC <br***@akanta.com> wrote:

一位同事有这样的代码：

类CMyObject {
//束会员职能
}

类CMyObjectList：public std :: vector< CMyObject>
{
//一群成员函数
}
我需要继承他的对象和列表的功能以及添加我自己的一些：

类CMyPersonalObject：public CMyObject
{
//更多东西
}

类CMyPersonalObjectList：public CMyObjectList
{
//更多东西
}

但是如果我将CMyPersonalObjectList传递给函数，然后尝试将CMyPersonalObject分配给该类型的局部变量，我得到编译器错误告诉我无法将CMyObject转换为CMyPersonalObject ...
编译器认为我传入的列表是由父对象组成的。

发生了什么以及如何解决它？
<谢谢，
B

Hi,

A colleague has some code like this:

class CMyObject {
// Bunch of Member functions
}

class CMyObjectList: public std::vector<CMyObject>
{
// Bunch of member functions
}

I need to inherit the functionality of his object and list as well as add
some of my own:

class CMyPersonalObject: public CMyObject
{
// More stuff
}

class CMyPersonalObjectList: public CMyObjectList
{
// More stuff
}

But if I pass in CMyPersonalObjectList to a function, and then try to
assign
the CMyPersonalObject to a local variable of that type, I get a compiler
error telling me that I cannot convert CMyObject to CMyPersonalObject...
the
compiler thinks the list I passed in is made of the parent objects.

What is going on and how do I fix it?

Thanks,
B

std :: vector是一个模板。 CMyObjectList也应该是一个模板，如果你想拥有个人对象列表，最低价格为
。


template< class T> CObjectList：public std :: vector< T> {

更多

};


typedef CObjectList< CMyPersonalObject> CMyPersonalObjectList;

-

grzegorz

std::vector is a template . CMyObjectList should also be a template, at
least if you want to have personalobject list.

template <class T> CObjectList : public std::vector<T> {
some more
};

typedef CObjectList<CMyPersonalObject> CMyPersonalObjectList;
--
grzegorz

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