How to Append Values to Lists in CMake: A Comprehensive Guide

CMake is a powerful tool that allows you to create build systems for various projects. One of its essential features is the ability to append values to lists. This can be achieved using the `APPEND` command, which enables you to add values to existing lists in your CMake script.

Why Append Values to Lists?

Appending values to lists in CMake is crucial because it allows you to manage complex build configurations with ease. By appending values to lists, you can create flexible and scalable build systems that cater to different platforms and toolchains.

Basic Syntax of APPEND Command

The basic syntax of the `APPEND` command is as follows:

```

APPEND

```

Where `` is the name of the list variable, and `` is the value you want to append to it. For example:

```

set(CMAKE_CXX_FLAGS_INIT '-coverage -fno-exceptions -g')

```

In this example, we are appending the values `-coverage`, `-fno-exceptions`, and `-g` to the `CMAKE_CXX_FLAGS_INIT` list.

Append Values with Spaces

One important thing to note is that when you append values with spaces, CMake treats them as separate items in the list. For instance:

```

set(CMAKE_CXX_FLAGS_INIT '-Werror -Wall -Wextra -Wpedantic')

```

In this example, we are appending four separate values `-Werror`, `-Wall`, `-Wextra`, and `-Wpedantic` to the `CMAKE_CXX_FLAGS_INIT` list.

Append Values to Target Properties

You can also append values to target properties using the `set_target_properties` command. For instance:

```

set_target_properties(my_target PROPERTIES LINKER_FLAGS '-lfoo -lname')

```

In this example, we are appending the values `-lfoo` and `-lname` to the `LINKER_FLAGS` property of the `my_target` target.

Best Practices

When working with CMake, it is essential to follow best practices to ensure that your build system is clean, portable, and future-proof. Here are some tips:

1. Avoid Adding Compiler Flags Explicitly: Instead of adding compiler flags explicitly via CMake, consider declaring them as constants using the `SET` command.

2. Use Toolchain Files: Toolchain files allow you to configure novel toolchains and separate the concern of describing how your artefacts are constituted from the concern of customising compiler flags.

3. Organise Source Files into Targets: Express instructions on how to organize source files into targets using CMakeLists.txt files, which should be entirely toolchain-agnostic.

In conclusion, appending values to lists in CMake is a powerful feature that enables you to create flexible and scalable build systems. By following best practices and understanding the basic syntax of the `APPEND` command, you can ensure that your build system is clean, portable, and future-proof.

Cmake list append