Python小技巧

测试积点老人

使用
查看python的内置函数"BIF"
BIF内建函数可以自动导入到__main__命名空间，但是内建函数都有自己的命名空间——即__builtins__，因此我们可以通过Python shell，然后通过如下命令查看所有的BIF：

1. <font size="2" style="font-weight: normal;">>>> dir(__builtins__)
   
2. ['ArithmeticError', 'AssertionError', 'AttributeError', 'BaseException', 'BufferError', 'BytesWarning',
   
3. 'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError', 'Exception', 'False',
   
4. 'FloatingPointError', 'FutureWarning', 'GeneratorExit', 'IOError', 'ImportError', 'ImportWarning',
   
5. 'IndentationError', 'IndexError', 'KeyError', 'KeyboardInterrupt', 'LookupError', 'MemoryError',
   
6. 'NameError', 'None', 'NotImplemented', 'NotImplementedError', 'OSError', 'OverflowError',
   
7. 'PendingDeprecationWarning', 'ReferenceError', 'RuntimeError', 'RuntimeWarning', 'StandardError',
   
8. 'StopIteration', 'SyntaxError', 'SyntaxWarning', 'SystemError', 'SystemExit', 'TabError', 'True',
   
9. 'TypeError', 'UnboundLocalError', 'UnicodeDecodeError', 'UnicodeEncodeError', 'UnicodeError',
   
10. 'UnicodeTranslateError', 'UnicodeWarning', 'UserWarning', 'ValueError', 'Warning', 'ZeroDivisionError',
    
11. '_', '__debug__', '__doc__', '__import__', '__name__', '__package__', 'abs', 'all', 'any', 'apply',
    
12. 'basestring', 'bin', 'bool', 'buffer', 'bytearray', 'bytes', 'callable', 'chr', 'classmethod', 'cmp', 'coerce',
    
13. 'compile', 'complex', 'copyright', 'credits', 'delattr', 'dict', 'dir', 'divmod', 'enumerate', 'eval', 'execfile',
    
14. 'exit', 'file', 'filter', 'float', 'format', 'frozenset', 'getattr', 'globals', 'hasattr', 'hash', 'help', 'hex', 'id',
    
15. 'input', 'int', 'intern', 'isinstance', 'issubclass', 'iter', 'len', 'license', 'list', 'locals', 'long', 'map', 'max',
    
16. 'memoryview', 'min', 'next', 'object', 'oct', 'open', 'ord', 'pow', 'print', 'property', 'quit', 'range',
    
17. 'raw_input', 'reduce', 'reload', 'repr', 'reversed', 'round', 'set', 'setattr', 'slice', 'sorted', 'static method',
    
18. 'str', 'sum', 'super', 'tuple', 'type', 'unichr', 'unicode', 'vars', 'xrange', 'zip']</font>

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然后，我们可以通过help(<object>)命令查看BIF内建函数的详细信息：

1. <font size="2" style="font-weight: normal;">>>> help(range)
   
2. Help on built-in function range in module __builtin__:
   
3. 
   
4. range(...)
   
5. range(stop) -> list of integers
   
6. range(start, stop[, step]) -> list of integers
   
7. 
   
8. Return a list containing an arithmetic progression of integers.
   
9. range(i, j) returns [i, i+1, i+2, ..., j-1]; start (!) defaults to 0.
   
10. When step is given, it specifies the increment (or decrement).
    
11. For example, range(4) returns [0, 1, 2, 3].  The end point is omitted!
    
12. These are exactly the valid indices for a list of 4 elements.
    
13. (END)</font>

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查看python的模块放置在计算机的什么地方打开python的命令行工具，

输入命令: >>> import sys; sys.path

输出如下(mac环境下)：

1. <span style="font-weight: normal;"><font size="2">['', '/Library/Python/2.7/site-packages/virtualenv-15.0.2-py2.7.egg', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python27.zip', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/PyObjC', '/Library/Python/2.7/site-packages']</font></span>

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Python的包管理器PyPI

PyPI是基于互联网的第三方Python模块存放的一个存储库。

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