3 ms·

Can you give an example of a use case where this is needed?

• codys 7y ago
  One place it's used is to avoid central "registration" for multiple "things". For example, consider a program with many fairly separate "subcommands". Using this mechanism allows adding a new subcommand simply by linking in a new source file (without changing a shared source file to list the new command).
  • berti 7y ago
    I use this idea in embedded work, where the code is split into "modules". The same firmware source is shared amongst various differing pieces of hardware, each of which utilise a different subset of modules.
• clort 7y ago
  This is used for constructor & destructor functions in C code. The function pointers get put in an array in a certain section which is collated then the startup and exit code calls them. Ordering is not guaranteed.
  • saagarjha 7y ago
    Note that the ordering that the constructors and destructors will be run once the binary has been constructed is guaranteed by your C runtime.
• jhallenworld 7y ago
  I like to use this technique for CLI command and help tables. It eliminates having a single giant table in a file, instead you have a C macro which makes the system aware of your command right next to your command definition. int my_command(..) { ... } COMMAND(my_command, "command_name", "example command") HELP("use --foo argument for this...") HELP("use --bar argument for that...") Also used this all the time back when I programmed assembly language. It's definitely a problem that this is not standardized. For example, TI has their own C compiler for their ARM CPUs, not everybody uses gcc..