What is a bytes-like object
Question:
In Python 3.6, the base64.b64encode() function requires "a bytes-like object, not str".
What is an example of a bytes-like object as opposed to a normal string?
Answers:
Anything that logically stores a sequence of bytes qualifies. That includes the actual bytes type, bytearray, mmap.mmap, array.array('B'), etc. str in Python 3 is a text type; the characters aren’t stored in a specified encoding, so you can’t use them as raw binary data directly; they must be encode-ed explicitly with a specific encoding.
For the technical definition, see the Python 3 glossary:
An object that supports the Buffer Protocol and can export a C-contiguous buffer. This includes all bytes, bytearray, and array.array objects, as well as many common memoryview objects. Bytes-like objects can be used for various operations that work with binary data; these include compression, saving to a binary file, and sending over a socket.
Some operations need the binary data to be mutable. The documentation often refers to these as “read-write bytes-like objects”. Example mutable buffer objects include bytearray and a memoryview of a bytearray. Other operations require the binary data to be stored in immutable objects (“read-only bytes-like objects”); examples of these include bytes and a memoryview of a bytes object.
In Python 3.6, the base64.b64encode() function requires "a bytes-like object, not str".
What is an example of a bytes-like object as opposed to a normal string?
Anything that logically stores a sequence of bytes qualifies. That includes the actual bytes type, bytearray, mmap.mmap, array.array('B'), etc. str in Python 3 is a text type; the characters aren’t stored in a specified encoding, so you can’t use them as raw binary data directly; they must be encode-ed explicitly with a specific encoding.
For the technical definition, see the Python 3 glossary:
An object that supports the Buffer Protocol and can export a C-contiguous buffer. This includes all
bytes,bytearray, andarray.arrayobjects, as well as many commonmemoryviewobjects. Bytes-like objects can be used for various operations that work with binary data; these include compression, saving to a binary file, and sending over a socket.Some operations need the binary data to be mutable. The documentation often refers to these as “read-write bytes-like objects”. Example mutable buffer objects include
bytearrayand amemoryviewof abytearray. Other operations require the binary data to be stored in immutable objects (“read-only bytes-like objects”); examples of these includebytesand amemoryviewof abytesobject.