Mastering Object-oriented Python

Filesystem and network considerations

As the OS filesystem (and network) works in bytes, we need to represent the values of an object's instance variables as a serialized stream of bytes. Often, we'll use a two-step transformation to bytes; we'll represent the state of an object as a string and rely on the Python string to provide bytes in a standard encoding. Python's built-in features for encoding a string into bytes neatly solves this part of the problem.

When we look at our OS filesystems, we see two broad classes of devices: block-mode devices and character-mode devices. Block-mode devices can also be called seekable because the OS supports a seek operation that can access any byte in the file in an arbitrary order. Character-mode devices ...