include_spip() includes a PHP file. The difference from PHP’s normal
include_once() is that the file is searched for in the SPIP
path, that is, in all the known directories and in the search priority order specified in the SPIP path.
include_spip() accepts 1 or 2 arguments and returns the address of the file found:
- the name or relative path of the file (without its .php extension)
- a flag called inclure (true by default) that indicates if the file is actually to be included, or if only the path of the file is to be returned.
- $address = include_spip('filename');
- $address = include_spip('filename', false); // inclusion is not performed