"Fredrik Lundh" <[EMAIL PROTECTED]> writes: > Ilpo Nyyssönen wrote: > >> What is the point in doing validation if it isn't done every time? Why >> wouldn't I do it every time? It isn't that slow thing to do. > > DTD validation is useful in two cases: [...]
I didn't mention DTD validation. Yes, I know the limitations of DTD validation. DTD validation gives a clear error message with line number in case of it doesn't match. Show me this: - An object oriented storage library - A flat thing is not enough, needs some hierarchy, like in XML - Validation that also converts the data to pythonic types, like numbers to ints or data of my objects to my objects - Includes a way to define version migration steps - Parsing and validation must be fast - Storage format preferably a readable text file - Easy to use in application These things would be nice to have in it too: - Multiple backends, at least text file, XML and SQL database - Some kind of synchronization or replication utilities >> Pickle doesn't have validation. I am not comfortable for using it as >> storage format that should be reliable over years when the program >> evolves. It also doesn't tell me if my program has put something other >> to the data than I meant to. > > But DTD validation doesn't tell you that either -- it's only concerned > with the structure, not the content. [...] Pickle doesn't have even that. Also I can't read pickle file without doing some program to dump it in readable format. So, I can't use validation to make sure the data in pickle is the one I want and I can't use less to see what is in the file. I really have NO IDEA what is in a pickle file. Or, yes, I clearly would need to build the validation myself on top of it! Not going to happen. > If you want the simplest thing, get rid of the DTD, and make your > loader ignore things that it doesn't recognize, use default values for > fields that are not required (or weren't in the format from the start), > and give a nice readable error message if something required is > missing. That'll give you a nice, portable, reliable, and extremely > future-proof design. So my program will just work in the wrong way if I make a typo to a non-required field when writing the file? No thanks. -- Ilpo Nyyssönen # biny # /* :-) */ -- http://mail.python.org/mailman/listinfo/python-list
