Hello, Object Library!

How to Create and Use The Object File in CMake

@Gitter :gitter.im/cnruby
Code ID: basic_137
Code Name: Hello, Object Library!

Youtube Video

Short Video

TABLE of CONTENTS

• About The Project
  • Explain The C++ Library Obejct of CMake
• Explain C++ and CMake Code
  • Explain Main's CMake Code
  • Explain Library's CMake Code
• A Demonstration of Building Project
  • The Difference for two build methods
• Final Summary
• References
  • Requirements
  • Get The Code with Shell Commands
  • The Structure of Folder

About The Project

Explain The C++ Library Obejct of CMake

// ./src/main.cxx
#include <iostream>
#include "config.hxx"
#include "header.hxx"
#include "macro.hxx"

int main(int, char**) {
  std::cout << "Project ID:\t\t\t" << PROJECT_NAME << std::endl;
  std::cout << "Project Code:\t\t\t" << PROJECT_DESCRIPTION << std::endl;
  std::cout << "Project Version:\t\t" << MACRO_VERSION << std::endl << std::endl;

  Header header;
  header.hello("Library");

Explain C++ and CMake Code

# ./src/one.cmake
add_executable(
  ${MAIN_NAME}_one
  main.cxx
)

---

# ./src/three.cmake
add_library(
  ${MAIN_NAME}_o
  OBJECT main.cxx
)
add_executable(
  ${MAIN_NAME}_three
)
target_link_libraries(
  ${MAIN_NAME}_three
  ${LIB_NAME}_o ${MAIN_NAME}_o
)

Explain Main's CMake Code

# ./lib/one.cmake
add_library(
  ${LIB_NAME}_a
  STATIC header.cxx
)

---

# ./lib/three.cmake
add_library(
  ${LIB_NAME}_o
  OBJECT header.cxx
)
add_library(
  ${LIB_NAME}_ar STATIC
)
target_link_libraries(
  ${LIB_NAME}_ar
  ${LIB_NAME}_o
)

Explain Library's CMake Code

A Demonstration of Building Project

The Difference for two build methods

Final Summary

感谢大家观看!

@Gitter: gitter.im/cnruby

@Github: github.com/cnruby

@Twitter: twitter.com/cnruby

@Blogspot: cnruby.blogspot.com

References

• https://stackoverflow.com/questions/8249945/what-is-object-in-object-file-and-why-is-it-called-this-way
• https://qiita.com/mrk_21/items/57075ce36f49ce0aacf4
• https://stackoverflow.com/questions/35696103/cmake-wildcard-for-target-objects
• https://stackoverflow.com/questions/44767099/linking-cmake-interface-libraries-with-object-libraries
• https://stackoverflow.com/questions/49265945/cmake-append-objects-from-different-cmakelists-txt-into-one-library
• https://stackoverflow.com/questions/58969829/cmake-object-files-of-executable-in-custom-command
• https://github.com/dev-cafe/cmake-cookbook
• https://www.dealii.org/9.1.1/users/cmakelists.html
• https://cmake.org/cmake/help/latest/manual/cmake-generator-expressions.7.html
• https://stackoverflow.com/questions/50684930/how-to-collect-object-files-o-in-a-particular-directory-with-cmake
• https://stackoverflow.com/questions/48296061/cmakes-objects-output-folder-variable
• https://stackoverflow.com/questions/29884856/how-to-get-path-to-object-files-with-cmake-for-both-multiconfiguration-generator

Requirements

• Ubuntu 20.04+
• VS Code 1.43.0+
• CMake 3.17.2+

Get The Code with Shell Commands

git clone https://github.com/cnruby/w3h1_cmake.git basic_137
cd basic_137
git checkout basic_137
code .

The Structure of Folder

# ./docs/output/tree.txt
.
├── cmake
│  ├── CMakeLists.txt
│  ├── config.h.in
│  ├── GetOutput.cmake
│  └── Initialize.cmake
├── CMakeLists.txt
├── config
   ├── config.hxx
│  └── macro.hxx
└── src
   ├── CMakeLists.txt
   ├── main.cxx
   ├── one.cmake
   └── three.cmake