程序結構如下，

本例主要使用std::unique_ptr封裝C++常用的pimpl idom，就是在cpp文件中用一個impl來封裝細節。實現部分可以隨意修改，但是保持接口部分不變。
這樣一來是節省編譯時間。
二來是隱藏實現到cpp。
程序代碼如下，
test/CMakeLists.txt

cmake_minimum_required(VERSION 2.6)if(APPLE)message(STATUS "This is Apple, do nothing.")set(CMAKE_MACOSX_RPATH 1)set(CMAKE_PREFIX_PATH /Users/aabjfzhu/software/vcpkg/ports/cppwork/vcpkg_installed/x64-osx/share ) elseif(UNIX)message(STATUS "This is linux, set CMAKE_PREFIX_PATH.")set(CMAKE_PREFIX_PATH /vcpkg/ports/cppwork/vcpkg_installed/x64-linux/share) endif(APPLE)project(wrapped_pimpl)set(CMAKE_CXX_STANDARD 20) set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-narrowing")add_definitions(-g)find_package(ZLIB)find_package(OpenCV REQUIRED ) find_package(Arrow CONFIG REQUIRED)find_package(unofficial-brotli REQUIRED) find_package(unofficial-utf8proc CONFIG REQUIRED) find_package(Thrift CONFIG REQUIRED)find_package(glog REQUIRED)find_package(OpenSSL REQUIRED)find_package(Boost REQUIRED COMPONENTSsystemfilesystemserializationprogram_optionsthread)find_package(DataFrame REQUIRED)if(APPLE)MESSAGE(STATUS "This is APPLE, set INCLUDE_DIRS") set(INCLUDE_DIRS ${Boost_INCLUDE_DIRS} /usr/local/include /usr/local/iODBC/include /opt/snowflake/snowflakeodbc/include/ ${CMAKE_CURRENT_SOURCE_DIR}/../include/ ${CMAKE_CURRENT_SOURCE_DIR}/../../../include) elseif(UNIX)MESSAGE(STATUS "This is linux, set INCLUDE_DIRS")set(INCLUDE_DIRS ${Boost_INCLUDE_DIRS} /usr/local/include ${CMAKE_CURRENT_SOURCE_DIR}/../include/ ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/) endif(APPLE)if(APPLE)MESSAGE(STATUS "This is APPLE, set LINK_DIRS")set(LINK_DIRS /usr/local/lib /usr/local/iODBC/lib /opt/snowflake/snowflakeodbc/lib/universal) elseif(UNIX)MESSAGE(STATUS "This is linux, set LINK_DIRS")set(LINK_DIRS ${Boost_INCLUDE_DIRS} /usr/local/lib /vcpkg/ports/cppwork/vcpkg_installed/x64-linux/lib) endif(APPLE)if(APPLE)MESSAGE(STATUS "This is APPLE, set ODBC_LIBS")set(ODBC_LIBS iodbc iodbcinst) elseif(UNIX)MESSAGE(STATUS "This is linux, set LINK_DIRS")set(ODBC_LIBS odbc odbcinst ltdl) endif(APPLE)include_directories(${INCLUDE_DIRS}) LINK_DIRECTORIES(${LINK_DIRS})file( GLOB test_file_list ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp) file( GLOB APP_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/../impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../include/*.h ${CMAKE_CURRENT_SOURCE_DIR}/../include/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/arr_/impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/http/impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/yaml/impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/df/impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/death_handler/impl/*.cpp)add_library(${PROJECT_NAME}_lib SHARED ${APP_SOURCES} ${test_file}) target_link_libraries(${PROJECT_NAME}_lib ${Boost_LIBRARIES} ZLIB::ZLIB glog::glog DataFrame::DataFrame ${OpenCV_LIBS}) target_link_libraries(${PROJECT_NAME}_lib OpenSSL::SSL OpenSSL::Crypto libgtest.a pystring libyaml-cpp.a libgmock.a ${ODBC_LIBS} libnanodbc.a pthread dl backtrace libzstd.a libbz2.a libsnappy.a re2::re2 parquet lz4 unofficial::brotli::brotlidec-static unofficial::brotli::brotlienc-static unofficial::brotli::brotlicommon-static utf8proc thrift::thrift arrow arrow_dataset)foreach( test_file ${test_file_list} )file(RELATIVE_PATH filename ${CMAKE_CURRENT_SOURCE_DIR} ${test_file})string(REPLACE ".cpp" "" file ${filename})add_executable(${file} ${test_file})target_link_libraries(${file} ${PROJECT_NAME}_lib) endforeach( test_file ${test_file_list})

test/pimpl_idom_test.cpp

#include "death_handler/death_handler.h" #include <glog/logging.h> #include "person1.h"#include <utility> #include <gtest/gtest.h>int main(int argc, char** argv) {FLAGS_log_dir = "./";FLAGS_alsologtostderr = true;// 日志級別 INFO, WARNING, ERROR, FATAL 的值分別為0、1、2、3FLAGS_minloglevel = 0;Debug::DeathHandler dh;google::InitGoogleLogging("./logs.log");testing::InitGoogleTest(&argc, argv);int ret = RUN_ALL_TESTS();return ret; }GTEST_TEST(WrappedPimplTests, WrappedPimpl) {Person p{"Zhang San"};p.greet(); }

include/pimpl.hpp

#ifndef _FREDRIC_PIMPL_HPP_ #define _FREDRIC_PIMPL_HPP_#include <memory>template <typename T> class PImpl { private:std::unique_ptr<T> p_impl; public:template <typename ... Args>PImpl(Args&& ... args): p_impl{new T(std::forward<Args>(args)...)} {}PImpl(): p_impl(new T()) {}~PImpl() {}T* operator->() {return p_impl.get();}T& operator*() {return *p_impl;} }; #endif

include/person1.h

#ifndef _FREDRIC_PERSON1_H_ #define _FREDRIC_PERSON1_H_#include "pimpl.hpp"#include <string>class Person { public:class PersonImpl;PImpl<PersonImpl> impl_;std::string name;Person(std::string const& name_);// 這個析構函數必須，否則可能會導致編譯器找不到PersonImpl的大小// 無法工作~Person();void greet(); }; #endif

include/person1.cpp

#include "person1.h"#include <iostream>class Person::PersonImpl{ public:void greet(Person* p); };void Person::PersonImpl::greet(Person* p) {std::cout << "Hello, my name is: " << p->name << "\n"; }Person::Person(std::string const& name_): name{name_}, impl_(){ }void Person::greet() {impl_->greet(this); }Person::~Person() {}

程序輸出如下，

總結

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