Chris Angelico <ros...@gmail.com> writes: > This is a distinction I generally make. Putting it another way: a list > has the same meaning regardless of how many items are on it (for > instance, a shopping list is still a shopping list whether it has five > or fifty items on it), where a tuple is a package where each element > has a specific meaning […]
Yes. The disctinction is even clearer, I find, by saying that the *meaning of the position* in the sequence is significant for a tuple, not significant for a list. That is, the ‘2’ in ‘cartesian_point = (2, 3)’ means something different than in ‘cartesian_point = (3, 2)’. Whereas the ‘2’ in ‘test_scores = [2, 3]’ means exactly the same as in ‘test_scores = [3, 2]’. If each position in the sequence gives the value there a different menaning, use a tuple; if not, use a list. > Nothing in the language enforces this, but the mutability of lists > does tend to align well with things that can grow and shrink, and the > immutability of tuples makes them more like strings or complex numbers > (in fact, a complex number is basically a tuple of two floats). Not only the growing and shrinking, but the re-ordering of items in a list should not change the meaning of its items. If you can ‘sort’ the sequence and the items still mean exactly what they did before, then a tuple is the wrong type to use, semantically. -- \ “Crime is contagious… if the government becomes a lawbreaker, | `\ it breeds contempt for the law.” —Justice Louis Brandeis | _o__) | Ben Finney -- https://mail.python.org/mailman/listinfo/python-list
