Davy a écrit : > Hi all, > > When reading Python source code of Peter Norvig's AI book, I found it > hard for me to understand the idea of slot (function nested in > function).
First point : this code seems to be based on an older (way older) Python version, so some things would not be done that way no more. Also, in newer (well... not that new, but...) Python versions, the term 'slot' has a quite different meaning (for short: a memory optimization for attributes...). FWIW, what the author names 'slots' here are really instance attributes - not the use of inner functions (please refer to the class's docstring and __init__ method code). > Please see "program()" nested in "make_agent_program()", > why not use program() directly? It's a local variable of make_agent_program, so unless you bind it to another name (which is done in the __init__), you can't access it from outside make_agent_program. The intent - which is explained in the docstring - is to make sure the 'program' function won't access the Agent instance - so it was obviously written for a Python version that predates lexical closures support (you can do some archeological research to find out when this support was added if you want !-). Now this implementation, whatever it was worth by the time this code was written (some 5 or more years ago AFAICT) would be considered a WTF with newer Python versions - where the obvious solution would be to define "program" as a staticmethod. HTH -- http://mail.python.org/mailman/listinfo/python-list
