Learning Python, 2nd Edition

Chapter 7. Tuples, Files, and Everything Else

This chapter rounds out our look at the core object types in Python, by introducing the tuple (a collection of other objects that cannot be changed), and the file (an interface to external files on your computer). As you’ll see, the tuple is a relatively simple object that largely performs operations you’ve already learned about for strings and lists. The file object is a commonly-used and full-featured tool for processing files; further file examples appear in later chapters of this book.

This chapter also concludes this part of the book by looking at properties common to all the core datatypes we’ve met—the notions of equality, comparisons, object copies, and so on. We’ll also briefly explore other object types in the Python toolbox; as we’ll see, although we’ve met all the primary built-in types, the object story in Python is broader than we’ve implied thus far. Finally, we’ll close this part with a set of common datatype pitfalls, and exercises that will allow you to experiment with the ideas you’ve learned.

Tuples

The last collection type in our survey is the Python tuple. Tuples construct simple groups of objects. They work exactly like lists, except that tuples can’t be changed in-place (they’re immutable) and are usually written as a series of items in parentheses, not square brackets. Although they don’t support any method calls, tuples share most of their properties with lists. Tuples are:

Ordered collections of arbitrary objects ...