1. A method for creating a computer programming library file containing at least one subroutine for performing a function to be used in a non-script programming language or to be run as a script in a script programming language, comprising the steps of: creating a library file having a predetermined given name in a predetermined program file; creating at least one subroutine having said given name; creating code configured to test the operability of said at least one subroutine, said code being placed in said library file and being executable only under predetermined conditions.