Extending the power of Pascal's external procedure mechanism

摘要

AbstractThe CDC Pascal 6000–3.4 compiler allows external procedures to be designed and compiled separately. Such a mechanism strongly enhances the extensibility of the language. However, the external procedures are restricted to having ‘fixed’ parameter list only and is therefore unsuitable for designing I/O routines. This paper describes a cheap way to release the restriction thereby extending the power of the external procedure mechanism significantly. The method is to include a new compiler option, called the Z option, to the existing Pascal compiler. The Z option allows a user to breach the strong binding between format and actual parameters while not diminishing program reliability. The main advantage is that the I/O system can now be isolated from the compiler. I/O features can be added and removed easily as with other library rou