Enable the user to configure a program is usually necessary. Im GUI programs it is often sufficient to provide a way to change the configuration through the user interface. But for all program it is generally better to also provide a means to provide a configuration through files.
Many formats exist, implemented through libraries with bindings for all languages. Formats like YAML or INI are commonly used but they have one limitation: they provide only static configuration possibilities.
Maybe the configuration should be dynamic. If the configuration allows defining functions the user can arbitrarily extend the configuration files. Implementing such an environment would be overkill. We could just use an existing scripting language.
One possible implementation is to use Lua. Lua is often used in C/C++ code as an extension language. The implementation is available in the form of a library and the code and runtime requirements are not big.
The code in this project allows to use Lua easily in C++ code. The code in
test.cc shows the use of the code and the Makefile shows how to compile
the code. One possible way to use the code:
- install a file like
configin a read-only in a data directory (e.g., in a per-project directory under/usr/share) - changable configuration files for the system (under
/etc) and in the user's home directory (under$HOME/.config) allow ample opportunity for customization
The locations of the configuration files and the files themselves can be predictable,
as it is the case in the provided config file.
Providing the possibility to add code to the configuration files adds risk. This form of configuration handling is not the right approach for all programs and/or situations. The risks and benefits must be weight.