一个CMake的例子

首先编写4个文件：

1、CMakeLists.txt内容：

cmake_minimum_required(VERSION 3.15)

project(Demo)

include_directories(${PROJECT_BINARY_DIR}/headers)
aux_source_directory(${PROJECT_BINARY_DIR}/sources SRC_DIR)

add_library(dynamic_library SHARED ${SRC_DIR})
add_library(static_library STATIC ${SRC_DIR})
set(LIBRARY_OUTPUT_PATH ${PROJECT_BINARY_DIR}/libs)

add_executable(demo_dynamic main.cc)
target_link_libraries(demo_dynamic dynamic_library)

add_executable(demo_static main.cc)
target_link_libraries(demo_static static_library)

add_compile_options(-std=c++17)

set(EXECUTABLE_OUTPUT_PATH ${PROJECT_BINARY_DIR}/bin)

2、sources/foo.cc内容：

#include <functional>
#include <iostream>

void (*fp1)() = []() {};
void (*fp2)() = []() { std::cout << "In fp2" << std::endl; };

3、headers/bar.h内容：

#include <functional>
#include <iostream>

void fp3() { std::cout << "In fp3" << std::endl; };

4、main.cc内容：

#include <functional>
#include <string>
#include <unordered_map>

#include "bar.h"

extern void (*fp1)();
extern void (*fp2)();
extern void fp3();

void calltable(
    const std::string &condition,
    std::unordered_map<std::string, const std::function<void(void)>> &table) {
  if (table.count(condition)) {
    table[condition]();
  }
}

int main(int argc, char *argv[]) {
  std::unordered_map<std::string, const std::function<void(void)>> table{
      {"1", fp1},
      {"2", fp2},
      {"3", fp3},
  };
  std::string condition = "1";
  calltable(condition, table);
  condition = "2";
  calltable(condition, table);
  condition = "3";
  calltable(condition, table);
}

然后编译、运行：

cmake . && make
./bin/demo_dynamic
./bin/demo_static