The CMake Configuration

Writing the Main CMake File

To link the Erbsland Configuration Parser with your application, we’ll create a top-level CMake configuration file that includes both the parser and your app directory.

We’ll start by creating the root CMakeLists.txt:

Create and open the file:
```
$ nano CMakeLists.txt
```

Add the following contents:

<project>/CMakeLists.txt

cmake_minimum_required(VERSION 3.25)
project(RobotEscapeProject)

add_subdirectory(erbsland-cpp-configuration)
add_subdirectory(robot-escape)

This file does the following:

Specifies the minimum CMake version: Ensures you’re using features available in CMake 3.25 or newer.
Names your project: Here, we call it RobotEscapeProject.
Adds subdirectories in order:
- erbsland-cpp-configuration: The parser library.
- robot-escape: Your application code.

CMake processes these in the order given, which means all libraries are available before compiling the app itself.

Setting Up the Application CMake File

Next, let’s set up the CMake configuration for your application specifically.

Create and open the application-level CMake file:
```
$ nano robot-escape/CMakeLists.txt
```

Add the following contents:

<project>/robot-escape/CMakeLists.txt

cmake_minimum_required(VERSION 3.25)
project(RobotEscapeApp)

add_executable(robot-escape
    src/main.cpp)

target_compile_features(robot-escape PRIVATE cxx_std_20)
target_link_libraries(robot-escape PRIVATE erbsland-configuration-parser)

This file does a few important things:

Defines your app as an executable using main.cpp as the entry point.
Enables C++20 using target_compile_features.
Links your app to the parser library, which was registered earlier by its CMake project name: erbsland-configuration-parser.

The Current Project State

At this point, your project directory structure should look like this, with the newly added components marked:

robot-escape
    ├── erbsland-cpp-configuration
    ├── robot-escape
    │   ├── src
    │   └── CMakeLists.txt           # [new] The application CMake file
    └── CMakeLists.txt               # [new] The main project CMake file

Write a Minimal Main Function →