python学习笔记——help()
http://www.cnblogs.com/itech/archive/2011/01/06/1929155.html
很多常用的python函数或模块，经常需要查看帮助，很不方便。
在python的交互命令行下使用help()或在python文件中调用help()函数可以很方便的查看帮助。
一 查看所有的关键字：help("keywords")
1 Here is a list of the Python keywords. Enter any keyword to get more help. 2 3 and elif import return 4 as else in try 5 assert except is while 6 break finally lambda with 7 class for not yield 8 continue from or 9 def global pass 10 del if raise
二 其他
查看python所有的modules：help("modules")
单看python所有的modules中包含指定字符串的modules： help("modules yourstr")
查看python中常见的topics： help("topics")
查看python标准库中的module：import os.path + help("os.path")
查看python内置的类型：help("list")
查看python类型的成员方法：help("str.find")
查看python内置函数：help("open")
三 例如查看copy模块帮助如下： help("copy")
1 Help on module copy: 2 3 NAME 4 copy - Generic (shallow and deep) copying operations. 5 6 FILE 7 c:\python31\lib\copy.py 8 9 DESCRIPTION 10 Interface summary: 11 12 import copy 13 14 x = copy.copy(y) # make a shallow copy of y 15 x = copy.deepcopy(y) # make a deep copy of y 16 17 For module specific errors, copy.Error is raised. 18 19 The difference between shallow and deep copying is only relevant for 20 compound objects (objects that contain other objects, like lists or 21 class instances). 22 23 - A shallow copy constructs a new compound object and then (to the 24 extent possible) inserts *the same objects* into it that the 25 original contains. 26 27 - A deep copy constructs a new compound object and then, recursively, 28 inserts *copies* into it of the objects found in the original. 29 30 Two problems often exist with deep copy operations that don't exist 31 with shallow copy operations: 32 33 a) recursive objects (compound objects that, directly or indirectly, 34 contain a reference to themselves) may cause a recursive loop 35 36 b) because deep copy copies *everything* it may copy too much, e.g. 37 administrative data structures that should be shared even between 38 copies 39 40 Python's deep copy operation avoids these problems by: 41 42 a) keeping a table of objects already copied during the current 43 copying pass 44 45 b) letting user-defined classes override the copying operation or the 46 set of components copied 47 48 This version does not copy types like module, class, function, method, 49 nor stack trace, stack frame, nor file, socket, window, nor array, nor 50 any similar types. 51 52 Classes can use the same interfaces to control copying that they use 53 to control pickling: they can define methods called __getinitargs__(), 54 __getstate__() and __setstate__(). See the documentation for module 55 "pickle" for information on these methods. 56 57 CLASSES 58 builtins.Exception(builtins.BaseException) 59 Error 60 ... ... 61 62 FUNCTIONS 63 copy(x) 64 Shallow copy operation on arbitrary Python objects. 65 66 See the module's __doc__ string for more info. 67 68 deepcopy(x, memo=None, _nil=[]) 69 Deep copy operation on arbitrary Python objects. 70 71 See the module's __doc__ string for more info. 72 73 DATA 74 __all__ = ['Error', 'copy', 'deepcopy']
