Python铸造与奇异类型转换

Question

我有一段代码，用来创建文件列表并按其大小排序。在这里：

class DataScript(object):

def __init__(self, index, name, size):
    self.index = index
    self.name = name
    self.size = size

def __cmp__(self, other):
    if hasattr(other, 'getKey'):
        return self.getKey().__cmp__(other.getKey())

def getKey(self):
    return self.size

def __iter__(self):
    return self

def __next__(self):
    self.index += 1
    try:
        return data[self.index - 1]
    except IndexError:
        self.idx = 0
        raise StopIteration  # Done iterating.


resultList = []
data = [d for d in os.listdir(dirpath) if '_DATA_TABLE' in d]
i=0
for file in data:
    fileinfo = os.stat(join(dirpath, file))
    file_obj = DataScript(i, file, float(fileinfo.st_size))
    if isinstance(file_obj, DataScript):
        resultList.extend(file_obj)

    i=i+1

items = resultList
for i in range(len(items)):
    for j in range(len(items) - 1 - i):
        item1 = items[j]
        item2 = items[j+1]
        if isinstance(item1, DataScript) and isinstance(item2, DataScript):
            if item1.__cmp__(item2)>0:
                items[j] = item2
                items[j+1] = item1
resultList = items

一切正常，但并不完全如预期的那样。最后的结果列表不是DataScript对象的排序列表，而是字符串。为什么？ 结果我最后的分类部分不起作用

Answer 1

你可能想append而不是extend：

for file in data:
    fileinfo = os.stat(join(dirpath, file))
    file_obj = DataScript(i, file, float(fileinfo.st_size))
    if isinstance(file_obj, DataScript):
        resultList.append(file_obj)  # append DataScript obj to your list

    i=i+1