Python 清除通过几个pickler.dump调用保存的pickle数据的干净方法

要取消使用几个pickler.dump调用保存的pickle数据，我们需要相同数量的调用来取消pickler.load。一种快速而肮脏的方法是使用如下的try-except块：

with open("data.pk", "wb") as f:
    pickler = pickle.Pickler(f)
    pickler.dump("message1")
    pickler.dump("message2")
    pickler.dump("message3")

with open("data.pk", "rb") as f:
    unpickler = pickle.Unpickler(f)
    while True:
        try:
            loaded_data = unpickler.load()
        except Exception:
            break
        print("loaded:", loaded_data)

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然而，在我看来，依靠异常处理来实现这一点似乎是一种廉价的黑客行为。这是一个好方法还是有更好的方法？如果我想提前知道所需的调用数，我是否应该在文件开头显式地保存它？

这是一个很好的方法；您只需读取文件存储的所有pickle

另一种方法是首先将对象计数写入文件：

with open("data.pk", "wb") as f:
    f.write((3).to_bytes(2, 'big'))  # 2 bytes gives you enough room for expansion
    pickler = pickle.Pickler(f)
    pickler.dump("message1")
    pickler.dump("message2")
    pickler.dump("message3")

with open("data.pk", "rb") as f:
    count = int.from_bytes(f.read(2), 'big')
    unpickler = pickle.Unpickler(f)
    for i in range(count):
        loaded_data = unpickler.load()
        print("loaded:", loaded_data)

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正如@Martijn Pieters所说，你目前的方法没有什么问题。如果您想使实际获取数据的代码更具可读性（即更简洁和“更干净”），可以创建一个函数来隐藏丑陋的细节：

import pickle

def unpickled_items(filename):
    """ Unpickle a file of pickled data. """
    with open(filename, "rb") as f:
        while True:
            try:
                yield pickle.load(f)
            except EOFError:
                break

# Create test file.
with open("data.pk", "wb") as f:
    pickler = pickle.Pickler(f)
    pickler.dump("message1")
    pickler.dump("message2")
    pickler.dump("message3")


loaded_data = [item for item in unpickled_items("data.pk")]
print("saved data:", loaded_data)