https://docs.python.org/3.4/library/functools.html
1. "A key function is a callable that accepts one argument and returns another value indicating the position in the desired collation sequence." x = ['x','z','q']; sort(key=str.upper) My understanding is that, x, y, .. are passed to the key function which converts it to upper case and returns the value, which is then sorted. So what does he mean by 'position in the desired..."? Position is 0, 1, 2.. upper is 'normalizing' the input and then sort gathers the values and sorts them.. so where is the 'key' function returning a position in the sorted- list.. or whatever.. what does a key function do? 2. lru_cache "Since a dictionary is used to cache results, the positional and keyword arguments to the function must be hashable." basically says that the args must be immutable and not subject to change because he's using the args as part of a key to the result? "To help measure the effectiveness of the cache and tune the maxsize parameter, the wrapped function is instrumented with a cache_info() function that returns a named tuple showing hits, misses, maxsize and currsize" What does he mean by 'instrument'? Just a 'helper' function or is it nested in lru_cache or structured in some special way. "An LRU (least recently used) cache works best when the most recent calls are the best predictors of upcoming calls (for example, the most popular articles on a news server tend to change each day)." What? So if article1 changes.. how does that predict anything..? If article1 is most popular, you want it in the cache, but it'll become most popular only after some time.. or is he saying that popular articles must be kicked out off the cache at the end of 24hrs? -- https://mail.python.org/mailman/listinfo/python-list
