Donn Cave <[EMAIL PROTECTED]> wrote: > Tuples and lists really are intended to serve two fundamentally > different purposes. > [...] > As I'm sure everyone still reading has already heard, the natural > usage of a tuple is as a heterogenous sequence. [...] A list of > command arguments is clearly homogeneous in this sense - any > sequence of strings is a valid input, so any slice of this sequence > must also be valid. (Valid in the type sense, obviously the value > and thus the result must change.) A tuple of time values, though, > must have exactly 9 elements, so it's heterogeneous in this sense, > even though all the values are integer. > > I have to confess that this wasn't obvious to me, either, at first, > and in fact probably about half of my extant code is burdened with > the idea that a tuple is a smart way to economize on the overhead of > a list. Somewhere along the line, I guess about 5 years ago? maybe > from reading about it here, I saw the light on this, and since then > my code has gotten easier to read and more robust.
Strangely, I learned this as I was learning the language, and understood it after reading the explanation a couple of times (I can't remember where I was reading it, but it must have been a decent guide). However, in the intervening time I'd forgotten this fundamental difference between the *purpose* of list and tuple. Thanks very much for this reminder. You've probably stopped me from writing a bunch of misguided code and realising 5 years too late :-) -- \ "Timid men prefer the calm of despotism to the boisterous sea | `\ of liberty." -- Thomas Jefferson | _o__) | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
