A new technique for improving the quality of computer programs
R. S. Scowen · International Conference on Software Engineering · 1979
A new rule is proposed for computer systems: Every item of data stored by a computer program should subsequently be read; if not, a program must state explicitly whenever it wishes to overwrite or destroy an unused value.This rule is unknown in previous computer systems, yet violations usually indicate a confusing, incorrect or inefficient program. Many programming errors also manifest themselves as violations of this rule. The idea has been tested on practical programs by modifying a compiler used at NPL. The results are encouraging: when programs are being developed sources of inefficiency are often indicated and many errors show themselves more rapidly. The new rule is no hindrance when writing clear well-structured programs, but confused or obscure programs are more difficult to get (almost!) working.The technique can be implemented in suitably designed hardware very cheaply and easily.