为什么base64.b64encode()返回字节对象? [英] Why does base64.b64encode() return a bytes object?

问题描述

base64.b64encode()的目的是将二进制数据转换为ASCII安全的文本".但是，该方法返回一个字节类型的对象:

The purpose of base64.b64encode() is to convert binary data into ASCII-safe "text". However, the method returns an object of type bytes:

>>> import base64
>>> base64.b64encode(b'abc')
b'YWJj'

简单地获取该输出并decode()很容易，但是我的问题是:base64.b64encode()返回bytes而不是str的意义是什么?

It's easy to simply take that output and decode() it, but my question is: what is a significance of base64.b64encode() returning bytes rather than a str?

推荐答案

base64.b64encode()函数的目的是将二进制数据转换为ASCII安全的文本"

The purpose of the base64.b64encode() function is to convert binary data into ASCII-safe "text"

Python对此表示不同意见-base64被故意分类为二进制转换.

Python disagrees with that - base64 has been intentionally classified as a binary transform.

这是Python 3中的一项设计决策，即强制字节和文本分开并禁止隐式转换. Python现在对此非常严格，以致bytes.encode甚至都不存在，因此b'abc'.encode('base64')会引发AttributeError.

It was a design decision in Python 3 to force the separation of bytes and text and prohibit implicit transformations. Python is now so strict about this that bytes.encode doesn't even exist, and so b'abc'.encode('base64') would raise an AttributeError.

该语言的观点是字节串对象已经被编码了.将字节编码为文本的编解码器不适合此范例，因为当您要从字节域转到文本域时，它是一个 decode .请注意，rot13编码也已从标准编码的列表中消失出于相同的原因-它不适合Python 3范例.

The opinion the language takes is that a bytestring object is already encoded. A codec which encodes bytes into text does not fit into this paradigm, because when you want to go from the bytes domain to the text domain it's a decode. Note that rot13 encoding was also banished from the list of standard encodings for the same reason - it didn't fit properly into the Python 3 paradigm.

还有一个性能参数:假设Python自动处理base64输出的解码，这是C代码从

There also can be a performance argument to make: suppose Python automatically handled decoding of the base64 output, which is an ASCII-encoded binary representation produced by C code from the binascii module, into a Python object in the text domain. If you actually wanted the bytes, you would just have to undo the decoding by encoding into ASCII again. It would be a wasteful round-trip, an unnecessary double-negation. Better to 'opt-in' for the decode-to-text step.

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