### Bracha on Monkey Patching

Gilad Bracha just gave an excellent overview of "monkey patching," or adding methods to a class from the outside, and other possible solutions to the same problem, none of which satisfy.

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John Baez' enthusiasm is infectious, and his perspective appealing:

It's sort of hilarious that Ferro was solving cubic equations before negative numbers were worked out. It should serve as a lesson: we mathematicians often work on fancy stuff before understanding the basics. Often that's why math seemss hard! But often it's impossible to discover the basics except by working on fancy stuff and getting stuck.â€”John Baez, This Week's Finds in Mathematical Physics, Week 261

OK, yes, I like this: New York Times columnist Paul Krugman's 1978 "paper" entittled "The Theory of Interstellar Trade" (PDF). (His blog post linked it last week.)

There are some good lines in there, including a citation of a later paper by the same author, a note of the difference between "relative generality" (of theorems) and "general relativity" (a physical theory).

Sadly, it seems the basic assumptionâ€”that the two trading planets are in the same inertial references frameâ€”oversimplifies, and the central results seem to be that, since the trading end-points remain stationary in this frame, insterstellar trade is no different from international or interplanetary trade.