Python:同时迭代dict和list

Question

我想编写一个可以迭代dict并list以相同方式迭代的函数,如下面的代码.但是,它不起作用,并指责iter不是迭代器.

def constructResult(*args):
    header = ''
    result = ''
    for arg in args :
        if isinstance(arg, dict) :
            iter = arg.items; #arg is a dict
        else:
            iter = arg #arg is a list 
        for (key,value) in iter :
            header = header + key + ","

注意:此函数的输入是dict或list.这是一个假设.

这是错误消息:

 File "./write-hole-collector.py", line 595, in constructResult
   for (key,value) in iter :
 TypeError: 'builtin_function_or_method' object is not iterable

Answer 1

您需要调用的dict.items()方法:

iter = arg.items()  #arg is a dict

否则你确实会得到一个异常,告诉你方法本身不可迭代:

>>> d = {}
>>> for key, value in d.items:  # not called
...     pass
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'builtin_function_or_method' object is not iterable

这是因为通过不调用该方法,您试图迭代方法对象,该方法对象不支持该操作.