This week we're making a good faith effort to describe the Prototype
pattern, the Factory Method pattern, and the concept of covariant return
types (that often mingles with Prototypes and Factory Methods) in two
pages each. Can it be done?

See my latest attempts at brevity at
Once, Weakly: http://www.semantics.org/weekly.html

The individual 2-pagers (or close enough) are at
Virtual Constructors and Prototype:
http://www.semantics.org/once_weakly/ck08_clone.pdf

Factory Method:
http://www.semantics.org/once_weakly/ck09_factorymethod.pdf

Covariant Return Types:
http://www.semantics.org/once_weakly/ck10_covariantreturn.pdf

Best regards,

Steve