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Copy pathlambdaErrorTest.cpp
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102 lines (89 loc) · 2.48 KB
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//
// Created by william on 2021/4/17.
//
#include "base.h"
using namespace std;
#define STR(T) #T
#define DEBUG_PRINT_THIS(T) \
T() \
{ \
printf("constructor of %s is called for (%p).\n", STR(T), this); \
} \
~T() \
{ \
printf("destructor of %s is called for (%p).\n", STR(T), this); \
}
/// SDK-G
// G的代码，编译时不依赖任何F的内容
class G
{
// 通过回调函数来调用F中提供的功能(不引入F的文件、也不产生编译依赖)
std::function<std::string(const std::string& name)> m_readFileFunc;
public:
void setFunc(std::function<std::string(const std::string& name)> func)
{
m_readFileFunc = func;
}
DEBUG_PRINT_THIS(G);
};
/// SDK-F
class FConfig
{
public:
// FConfig的一些公用函数(可能来自于其他SDK)
std::function<std::string(const std::string&)> _readFileFunc;
std::shared_ptr<G> m_pG; // 出于某些需求，需要通过FConfig来传递G的对象。
std::string readFile(const std::string& name)
{
assert(_readFileFunc);
return _readFileFunc(name);
}
DEBUG_PRINT_THIS(FConfig);
};
class F
{
public:
void createG(const std::shared_ptr<FConfig>& config)
{
assert(config.use_count() == 1); // 引用传递config，不产生拷贝、引用计数不更改
m_pG = std::make_shared<G>();
m_pG->setFunc(
[&config](const std::string& name)->std::string
{
assert(config);
return config->readFile(name);
}
);
assert(config.use_count() == 1);
}
void init()
{
std::shared_ptr<FConfig> config = std::make_shared<FConfig>();
// 此处省略对config的初始化
assert(config.use_count() == 1);
createG(config);
assert(config.use_count() == 1);
config->m_pG = m_pG;
assert(m_pG.use_count() == 2);
config.reset();
assert(config == nullptr); // 实际未调用FConfig的析构函数。
assert(m_pG.use_count() == 1); // pG引用计数应该为1、实际为2.
}
DEBUG_PRINT_THIS(F);
private:
std::shared_ptr<G> m_pG;
};
/// APP
void lambdaErrorTest()
{
auto f = std::make_shared<F>();
f->init();
f.reset(); // 此时，G和FConfig的析构函数没有调用
}
/*
以下为程序输出
constructor of F is called for (0x95de80).
constructor of FConfig is called for (0x95eec0).
constructor of G is called for (0x95ef10).
destructor of F is called for (0x95de80).
*/