python之使用 else 子句处理异常

Python 教程 states:

The try ... except statement has an optional else clause, which, when present, must follow all except clauses. It is useful for code that must be executed if the try clause does not raise an exception. For example:

for arg in sys.argv[1:]: 
    try: 
        f = open(arg, 'r') 
    except IOError: 
        print 'cannot open', arg 
    else: 
        print arg, 'has', len(f.readlines()), 'lines' 
        f.close() 

The use of the else clause is better than adding additional code to the try clause because it avoids accidentally catching an exception that wasn’t raised by the code being protected by the try ... except statement.

问题1> A＆tej 看了上面的文档，还是不明白为什么不能简单的把代码从else子句移到try子句中。