Dive into python学习笔记

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1.第一个程序odbchelper.py

 def buildConnectionString(params):
     """Build a connection string from a dictionary

     Returns string.
     """
     return ";".join(["%s=%s" % (k, v) for k, v in params.items()])

 if __name__ == "__main__":
     myParams = {"server":"mpilgrim", \
                 "database":"master", \
                 "uid":"sa", \
                 "pwd":"secret"
                 }
     print buildConnectionString(myParams)

关键点理解：

1.三重引号

"""Build a connection string from a dictionary
 
 Returns string.
 """
常用于定义doc string，文档化python函数

2.  ";".join(["%s=%s" % (k, v) for k, v in params.items()])

params.items()表明params必然是directory，调用items()方法返回键值对元组列表，利用多重赋值取出键值(k,v)元组，然后调用字符串对象的join方法将这些键值对用；隔开，join方法将list中的元素连接成单个字符串，打印的结果也就不再是列表的形式；注：join只能用于元素师字符串的list

运行结果为：server=mpilgrim;uid=sa;database=master;pwd=secret

附：split与join正好相反，它是将一个字符串分割成多元素list

>>>s.split(";") (1)

['server=mpilgrim', 'uid=sa', 'database=master', 'pwd=secret']

3.if __name__ == "__main__":用于测试模块

2.自省apihelper.py

 def info(object, spacing=10, collapse=1):
     """Print methods and doc strings.

     Takes module, class, list, dictionary, or string."""
     methodList = [e for e in dir(object) if callable(getattr(object, e))]
     processFunc = collapse and (lambda s: " ".join(s.split())) or (lambda s: s)
     print "\n".join(["%s %s" %
                      (method.ljust(spacing),
                       processFunc(str(getattr(object, method).__doc__)))
                      for method in methodList])

 if __name__ == "__main__":
     print help.__doc__