I've been wondering recently whether Python could benefit from having an "instance" statement which does for instances what the "class" statement does for classes.
The idea is you'd be able to say something like
instance isSpecification(model.Field): isRequired = 1 qualifiedName = 'Foundation.Core.ModelElement.isSpecification'
and it would be equivalent to
isSpecification = model.Field(isRequired = 1, qualifiedName = 'Foundation.Core.ModelElement.isSpecification')
One of the use cases I have in mind is GUI programming, where you frequently need to build complicated nested structures with lots of keyword arguments to constructors. A construct like this might help you to lay out the code more neatly and readably.
-1. TOOWTDI. --Guido van Rossum (home page: http://www.python.org/~guido/)