Antoon Pardon <[EMAIL PROTECTED]> writes: > Op 2005-01-18, Simon Brunning schreef <[EMAIL PROTECTED]>: > > On 18 Jan 2005 07:51:00 GMT, Antoon Pardon <[EMAIL PROTECTED]> wrote: > >> 3 mutating an item in a sorted list *does* *always* cause problems > > > > No, it doesn't. It might cause the list no longer to be sorted, but > > that might or might no be a problem. > > Than in the same vain I can say that mutating a key in a dictionary > doesn't always cause problems either. Sure it may probably make a > key unaccessible directly, but that might or might not be a problem.
Well, I'd definitely consider an inaccessible key as constituting a problem, but I don't think that's a good analogy to the list case. With the dictionary, the change can (though I do agree it does not have to) interfere with proper operation of the dictionary, while a list that is no longer sorted still functions perfectly well as a list. That is, I feel "problems" are more guaranteed with a dictionary since we have affected base object behavior, whereas sorted is not an inherent attribute of the base list type but something the application is imposing at a higher level. For example, I may choose to have an object type that is mutable (and not worthy for use as a dictionary key) but maintains a logical ordering so is sortable. I see no problem with sorting a list of such objects, and then walking that list to perform some mutation to each of the objects, even if along the way the mutation I am doing results in the items so touched no longer being in sorted order. The act of sorting was to provide me with a particular sequence of objects, but aside from that fact, the list continues to perform perfectly well as a list even after the mutations - just no longer delivering objects in sorted order. -- David -- http://mail.python.org/mailman/listinfo/python-list
