On Thu, Feb 11, 2010 at 3:08 AM, Simon Brunning <simon@brunningonline.net> wrote:
2010/2/10 Gerald Britton <gerald.britton@gmail.com>:
Lastly, for completeness, I suppose copy() might be appropriate for both tuple and deque as well.
Why would you want to copy a tuple?
Say you had a problem where you started with a basic tuple, then needed to add items to it to produce some result. Now suppose you want to do that repeatedly. You don't want to disturb the basic tuple, so you make a copy of it before extending it. e.g.
country = ("US",) country_state = tuple(country)+("NY",) country_state_city = tuple(country_state) + ("NY",) country ('US',) country_state ('US', 'NY') country_state_city ('US', 'NY', 'NY')
if tuple() had a copy() method, I could write: country_state = country.copy() + ("NY",) etc. Not that this is necessarily "better" in some way. I'm just thinking about consistency across the built-in types. If dict() and set() have copy(), why not list() and tuple()? On the other hand, if the consensus is _not_ to add the copy() method to lists and tuples, why not deprecate the method in sets and dicts and encourage folks to use the copy module or just use "newdict = dict(olddict)" and "newset = set(oldset)" to build a new dictionary or set from an existing one?
-- Cheers, Simon B. _______________________________________________ Python-ideas mailing list Python-ideas@python.org http://mail.python.org/mailman/listinfo/python-ideas
-- Gerald Britton