* provide an easy way to sort lists of pointers (without having to make a custom '<' operator each time).* Easy way to specify different comparison operators for various subfields. ie. in stead of one complex '<' operator, specify one for each subfield and then define sortorder (which subfield first, ...) on sorttime. * provide a good set of default '<' operators. at least: - simple types (strings, numbers, ...) - pointers to simple types - pairs of the above * Specify ascending vs. descending sorting. Trivial criteria really, but reduces complexity (or number) of the '<' operators. * return the n highest/lowest only. (optimized, ie: not full sort and then cutting solution) First, to sort a list of pointers, they already have operator< defined, as
Michael Lacher wrote: they are a built in type. If the keys were pointers to arrays, then that problem can be solved by multikey wuicksoprt, which I am currently writing, which is a mix of quicksort and radixsort that works on keys that are arrays or vectors. Then, to specify various operator<s for different fields, you would use normal radix sort, (not using operator<,.but a byte extraction function) and you would start with the least significant field using the varaible bit radixsort, sort only using it, and pass the byte extraction the function. Then you would sort by the second least significant subfield, and pass whatever byte extraction function you wanted. However, to make that process much more simple, I will implement a version of radixsort and radix quicksort that allows you to pass more than one function(you will still hve to do a little bit of extra work).