Hi Marc, > > > a number of modules (like the hash module or the list module) allow > > > the user to specify callbacks (e.g. a comparison function). > > > Unfortunately, these procedures do not take a context parameter, which > > > can be a problem because C lacks closures. > > > > Is this a practical, actual problem, or only a theoretical one? > > It is a practical one; in a computer algebra application, I have lots > of small entities (two words each), whose sort order is determined by > the extra data.
OK. Then let's take the problem seriously. I think it's time to solve the problem once and for all. I propose to add a module that defines a function 'partial_function_last' such that, when you have a function pointer int (*cmp3) (void *arg1, void *arg2, void *context) then cmp2 = partial_function_last (cmp3, context); produces a function pointer int (*cmp2) (void *arg1, void *arg2) that invokes cmp3 with the given context. Wikipedia calls it "partial function application". The module will also have a function 'partial_function_free' that frees a function that was constructed in this way. Give me a couple of days to implement that. Bruno
