[EMAIL PROTECTED] (Alex Martelli) writes: > You could make a case for a "2D coordinate" class being "sufficiently > primitive" to have immutable instances, of course (by analogy with > numbers and strings) -- in that design, you would provide no mutators, > and therefore neither would you provide setters (with any syntax) for x > and y, obviously. However, a framework for 2D geometry entirely based > on immutable-instance classes would probably be unwieldy
Skencil's basic objects for 2d geometry, points and transformations, are immutable. It works fine. Immutable object have the great advantage of making reasoning about the code much easier as the can't change behind your back. More complex objects such as poly bezier curves are mutable in Skencil, and I'm not sure anymore that that was a good design decision. In most cases where bezier curve is modified the best approach is to simply build a new bezier curve anyway. Sort of like list-comprehensions make it easier to "modify" a list by creating a new list based on the old one. Bernhard -- Intevation GmbH http://intevation.de/ Skencil http://skencil.org/ Thuban http://thuban.intevation.org/ -- http://mail.python.org/mailman/listinfo/python-list
