“预期类型‘Union[str, bytearray]’改为‘int’”写入方法中的警告

Question

我的脚本使用预先生成的数据模式逐块写入文件：

#  Data pattern generator    
def get_random_chunk_pattern():
            return ''.join(random.choice(ascii_uppercase + digits + ascii_lowercase) for _ in range(8))

....

# DedupChunk class CTOR:
class DedupChunk:
    def __init__(self, chunk_size, chunk_pattern, chunk_position=0, state=DedupChunkStates.PENDING):
        self._chunk_size = chunk_size  # chunk size in bytes
        self._chunk_pattern = chunk_pattern
        self._chunk_position = chunk_position
        self._state = state
        self.mapping = None

    @property
    def size(self):
        return self._chunk_size

    @property
    def pattern(self):
        return self._chunk_pattern

    @property
    def position(self):
        return self._chunk_position

    @property
    def state(self):
        return self._state

....

# Here Chunk object is being initialized (inside other class's CTOR):
chunk_size = random.randint(64, 192) * 1024  # in bytes
        while (position + chunk_size) < self.file_size:  # generating random chunks number
            self.chunks.append(DedupChunk(chunk_size, DedupChunkPattern.get_random_chunk_pattern(), position))

....

# Actual writing
    with open(self.path, 'rb+') as f:
        for chunk in self.chunks:
            f.write(chunk.pattern * (chunk.size // 8))

PyCharm

在写入方法中显示“

Expected type 'Union[str, bytearray]'  got 'int' instead

”警告

但是当删除除法时

f.write(chunk.pattern * chunk.size)

，或者在外面做除法：

chunk.size //= 8
f.write(chunk.pattern * chunk.size)

警告消失

这里到底发生了什么？

谢谢

Answer 1

忽略此警告。 IDE 正在（根据有限的信息）对运行时的数据类型进行最佳猜测，但它的猜测是错误的。也就是说，如果您不知道某个东西实际上是什么，则可以相当合理地预期某个东西乘以

int

将得到

int

。

如果您确实想解决这个问题，请通过为您的类编写文档字符串（或使用注释来提供类型提示）来告诉 IDE 您的期望

chunk.pattern

。

例如。

class DedupChunk:
    """
    :type _chunk_pattern: str
    ... other fields
    """
    ... # rest of class

对于较新版本的 python，首选语法是：

class DedupChunk:
    def __init__(self,
            chunk_pattern: str,
            # ... more args
    ):
        self._chunk_pattern = chunk_pattern
        ... # rest of class

对于局部变量或类变量，您可以对变量进行注释。

# given f() has an unknown return type

foo: str = f()  # annotate as type str and initalise
bar: str        # only annotate as type str, but leave uninitialised

class MyClass:
    foo: str = f()
    bar: str

Answer 2

要忽略内联警告，请将此注释添加到导致警告的行上方

# noinspection PyTypeChecker

Answer 3

我遇到这个问题是因为我使用了

x=int|list[int]

而不是

x:int|list[int]