Advanced Topics in Exception Handling Techniques

The subject of exception handling, though it has its roots in programming language design, can and I suggest should be viewed in more general terms. It is of course at base just another “divide and conquer” approach to coping with complexity – originally just the complexity of conventional (sequential) programs. Well-designed language constructs allied to sanitary programming languages enable programmers to simplify their task by identifying and dealing separately with various predictable but uncommon situations – typically error situations. Each such situation, described perhaps by a set of logical preconditions, can have its own separately coded exception handler associated with it, designed to deal just with these particular pre-conditions, and if possible to achieve the desired post-conditions. The fact that this might not always be possible leads naturally to the idea of having various different sets of post-conditions, one for the normal (assumed to be error-free) situation, the others for various separate pre-defined error states. These other post-conditions can then, if appropriate, lead to exception handling at a higher level.