On Sun, Jun 4, 2017 at 9:42 AM, Jon Forrest <nob...@gmail.com> wrote: > On 6/3/2017 12:38 PM, Thomas Jollans wrote: > >>> I'd like to suggest an explanation of what a sequence is >>> that doesn't use the word 'object' because an object has >>> a specific meaning in Python. >>> >>> Am I on the right track here? >> >> No, strings don't internally store the characters as objects, and yes, >> the slicing operation creates objects. However, strings *are* sequences, >> sequences *are* ordered collections of objects. > > I don't see how both can be true. "Object" has a clear meaning in > Python, and the contents of a sequence don't meet the requirements, > as I understand them. > > If there were some way of measuring the number of objects in > a program, then it would be easy to prove (or disprove) my hypothesis. > In other words this program > > a = "abc" > > would have the same number of objects as this program > > a = "abcdefghijklmnopqrstuvwzyz"
A sequence doesn't necessarily "contain" anything. As has been mentioned, a range object is a sequence, but it creates integer objects lazily. The point of a sequence is that you can do this: for thing in sequence: and whatever is in 'thing' must, by definition, be an object. Since you can do this with a string, a string is, indeed, a sequence. (Technically there's more to a sequence than just being iterable, but this is the part that matters here.) The semantics of Python would be the same if all those objects were indeed pre-created, but for memory efficiency, they aren't. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
