设计模式，学以致用—Proxy模式

[root@Shentar /myprogs/cpp/proxy]# cat sysbase.h 
#ifndef _SYS_BASE_H_
#define _SYS_BASE_H_

class SysBase
{
public:
    SysBase(){}
    ~SysBase(){}
    virtual void doSmth() = 0;

};

#endif
[root@Shentar /myprogs/cpp/proxy]# cat interface.h
#ifndef _INTER_FACE_H__
#define _INTER_FACE_H__

#include "sysbase.h"

class InterFace : public SysBase
{
public:
    InterFace();
    ~InterFace();

    virtual void doSmth();

};


#endif

 

[root@Shentar /myprogs/cpp/proxy]# l libinterface.so 
-rwxrwxr-x 1 root root 9563 2013-11-16 13:30 libinterface.so

[root@Shentar /myprogs/cpp/proxy]# cat newinterface.h
#ifndef _NEW_INTERFACE_H_
#define _NEW_INTERFACE_H_

class InterFace;

class NewInterFace : public InterFace
{
    public:
        NewInterFace() : InterFace(){}
        ~NewInterFace(){}

    public:
        virtual void doSmth();

};


#endif
[root@Shentar /myprogs/cpp/proxy]# cat newinterface.cpp 
#include <stdio.h>
#include <stdlib.h>
#include "interface.h"
#include "newinterface.h"

void NewInterFace::doSmth()
{
    printf("do some extra initianize()!\n");
    InterFace::doSmth();
}

[root@Shentar /myprogs/cpp/proxy]# cat Makefile 
all:libinterface libnewinterface

libinterface:
    g++ -fPIC -g -shared -o libinterface.so interface.cpp

libnewinterface:
    g++ -fPIC -g -shared -L./ -linterface -o libnewinterface.so newinterface.cpp

[root@Shentar /myprogs/cpp/proxy]# cat proxyinterface.h
#ifndef _PROXY_INTERFACE_H_
#define _PROXY_INTERFACE_H_

#include "sysbase.h"

class ProxyInterFace : public SysBase
{
    public:
        ProxyInterFace(); 
        ~ProxyInterFace();

    public:
        virtual void doSmth();
        
    private:
        SysBase* pimpl;
};


#endif
[root@Shentar /myprogs/cpp/proxy]# cat proxyinterface.cpp 

#include <stdio.h>
#include <stdlib.h>
#include "interface.h"
#include "proxyinterface.h"

ProxyInterFace::ProxyInterFace() : SysBase()
{
    pimpl = new InterFace;
}

ProxyInterFace::~ProxyInterFace()
{
    delete pimpl;
    pimpl = NULL;
}

void ProxyInterFace::doSmth()
{
    printf("do some extra initianize()!\n");
    pimpl->doSmth();
}

[root@Shentar /myprogs/cpp/proxy]# cat test.cpp 
#include "sysbase.h"
#include "proxyinterface.h"

int main(int argc, char** argv)
{
    SysBase* p = new ProxyInterFace;
    p->doSmth();
    delete p;

    return 0;
}
[root@Shentar /myprogs/cpp/proxy]# cat Makefile 
all:libinterface libnewinterface proxyinterface test

libinterface:
    g++ -fPIC -g -shared -o libinterface.so interface.cpp

libnewinterface:
    g++ -fPIC -g -shared -L./ -linterface -o libnewinterface.so newinterface.cpp

proxyinterface:
    g++ -fPIC -g -shared -L./ -linterface -o libproxyinterface.so proxyinterface.cpp

test:
    g++ -fPIC -g -L./ -linterface -lproxyinterface -o testproc test.cpp
[root@Shentar /myprogs/cpp/proxy]# make all
g++ -fPIC -g -shared -o libinterface.so interface.cpp
g++ -fPIC -g -shared -L./ -linterface -o libnewinterface.so newinterface.cpp
g++ -fPIC -g -shared -L./ -linterface -o libproxyinterface.so proxyinterface.cpp
g++ -fPIC -g -L./ -linterface -lproxyinterface -o testproc test.cpp
[root@Shentar /myprogs/cpp/proxy]# ./testproc 
do some extra initianize()!
InterFace's doSmth is called!

从上面的客户使用的过程来看，真正做到了客户对原有接口不可见，做到了隔离，也就是做了保护代理。设计模式不是死的，不是一纸空谈。需要活学活用，需要在实践中积累。