Mpp::Signature::md5 -- Mpp::Signature class based on MD5 checksum
Unlike the usual signature class, this class computes an MD5 checksum of all input files. The date on your source file may change, but if you use this signature class, makepp will realize that no rebuild is necessary as long as the contents have not changed. Just make sure that no build time is actually written into the files themselves.
For C/C++ sources, Mpp::Signature::c_compilation_md5 is more suitable, since it ignores comments and whitespace. That compilation method is used by default if the statement is recognized as C compilation.