[FRIAM] div. zero bugs?

[Marcus G. Daniels]

phil henshaw wrote:
> What do you guys call the class of programming errors that act like 
> viruses in multiplying the complexity of a program's calculations to 
> the point of overwhelming the machine, logical flaws that have the 
> effect of dividing by zero.   
One class of exceptions I'd call "passing the buck".   "I don't know 
what to do so I'll go through some obligatory motions and give this to 
the caller"  (Inserting some junk code to show they thought about the 
possibility for a few seconds.)   Sooner or later a user of the library 
code and punts and ignores the whole thing and then some potentially 
weird failure occurs a bit later.   In C, for example, this idiom:

if ((ptr = malloc (100)) == NULL) return -1;

[A memory allocation failure is pretty much always fatal anyway -- they 
might as well just abort so the failure is localized when someone looks 
at it in a debugger.   Instead of it sneaking away by a few layers of 
indirection.]

In Common Lisp, and to some extent in Java, there is an orthogonal 
technique for dealing with exceptions.   Any code that can fail can 
signal a hierarchy of exception types, and then user can (or must) trap 
them with separate code.    Common Lisp fully separates signaling, 
handling, and recovery in a nice object-oriented way:

  
http://www.gigamonkeys.com/book/beyond-exception-handling-conditions-and-restarts.html