[英]Unresolved external symbol on virtual function
Each of these classes are in separate dll modules: 这些类中的每一个都在单独的dll模块中:
class Base
{
public:
virtual void foo();
void bar();
};
class Derived : public Base
{
public:
// override Base::foo()
void foo();
};
In Other.cpp: 在Other.cpp中:
#include "Derived.h"
The module that contains Derived links with Base.lib (not shown are the export/import directives). 包含带有Base.lib的派生链接的模块(未显示的是export / import指令)。 The module that contains Other.cpp links with Derived.lib, but not Base.lib.
包含Other.cpp的模块与Derived.lib链接,但不与Base.lib链接。 Up to this point, everything works fine.
到目前为止,一切正常。
However, if I change Base::bar() to be virtual and do not make a change to Derived, then the linker complains when linking Other.dll: 但是,如果我将Base :: bar()更改为虚拟并且不对Derived进行更改,则链接器在链接Other.dll时会抱怨:
Other.obj : error LNK2001: unresolved external symbol "public: virtual void __thiscall Base::bar()" ...
The only solutions I have found is to override Base::bar() in Derived or to have Other.dll also link with Base.lib. 我发现的唯一解决方案是覆盖Derived中的Base :: bar()或让Other.dll也与Base.lib链接。 Both solutions are not desired because they add client requirements when the server changes.
不需要这两种解决方案,因为它们会在服务器更改时增加客户端要求。
Any ideas on a better way to access/define the base class virtual methods in this scenario? 在这种情况下,有什么更好的方法来访问/定义基类虚拟方法的想法吗?
What's happening is that virtual Base::bar
needs to be in the vtable of a Derived, since there's no Derived::bar
. 发生的事情是
virtual Base::bar
必须位于Derived的vtable中,因为没有Derived::bar
。
I don't understand your comment about "client requirements when the server changes". 我不理解您对“服务器更改时的客户端要求”的评论。 I don't see how base/derived maps to client/server.
我看不到基本/派生到客户端/服务器的映射。 They're two independent dimensions to me.
对我来说,它们是两个独立的维度。
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