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

这里究竟发生了什么？

谢谢

Answer 1

忽略此警告。 IDE 正在对运行时的数据类型做出最佳猜测（根据有限的信息），但它猜错了。也就是说，如果您不知道某物实际是什么，则期望某物乘以 int 将产生 int 是相当合理的。

如果你真的想解决这个问题然后告诉 IDE 你期望 chunk.pattern 是什么通过为你的 class 写一个文档字符串（或使用注释来提供类型提示).

例如

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

使用较新版本的 python，则首选语法为：

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 class 变量，您可以注释变量。

# 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，请在导致警告的行上方添加此注释

# noinspection PyTypeChecker

"Expected type 'Union[str, bytearray]' got 'int' instead" 写入方法中的警告

"Expected type 'Union[str, bytearray]' got 'int' instead" warning in write method

python

pycharm

python-2.7