Core Python Programming (2nd Edition)

9.1. File Objects
File objects can be used to access not only normal disk files, but also any other type of "file" that uses
that abstraction. Once the proper "hooks" are installed, you can access other objects with file-style
interfaces in the same manner you would access normal files.
You will find many cases where you are dealing with "file-like" objects as you continue to develop your
Python experience. Some examples include "opening a URL" for reading a Web page in real-time and
launching a command in a separate process and communicating to and from it like a pair of
simultaneously open files, one for write and the other for read.
The open() built-in function (see below) returns a file object that is then used for all succeeding
operations on the file in question. There are a large number of other functions that return a file or filelike
object. One primary reason for this abstraction is that many input/output data structures prefer to
adhere to a common interface. It provides consistency in behavior as well as implementation. Operating
systems like Unix even feature files as an underlying and architectural interface for communication.
Remember, files are simply a contiguous sequence of bytes. Anywhere data need to be sent usually
involves a byte stream of some sort, whether the stream occurs as individual bytes or blocks of data.