[Python-ideas] get method for sets?

[Cameron Simpson]

On 16May2012 17:42, Stephen J. Turnbull <stephen at xemacs.org> wrote:
| Mike Meyer writes:
|  > On Wed, 16 May 2012 17:26:45 +1000
| 
|  > > Could this helper function not do the job?
|  > > 
|  > > def get(s):
|  > >     x = s.pop()
|  > >     s.add(x)
|  > >     return x
|  > 
|  > Sure, if you don't mind munging the set unnecessarily. That's more
|  > readable, but slower and longer than:
|  > 
|  > def get(s):
|  >     for x in s:
|  >         return s

I was about to suggest Mike's implementation.

| Why would you mind munging the set temporarily?

Personally, I work with multiple threads quite often. Therefore I
habitually avoid data structure modifying operations unless they're
neccessary. Any time I modify a data structure is a time I have to worry
about shared access.

| Why is speed (of
| something that almost by definition is undefined if repeated)
| important?

Besides, modifying a data structure _is_ slow than just looking,
usually. There may even be garbage collection:-(

| I'm -1 on adding a method that has no motivation in production that I
| can see.  Just redefine your get() function as a function, with a more
| appropriate name such as "get_item_nondeterministically".  It will
| work on any iterable.  (Don't forget to document that it will "use up"
| an item if the iterable is not a sequence, though.)

Yah:

  def an(s):
    for i in s:
      return i

I'm also -1 on a set _method_, though he can always subclass and add his
own for his use case.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au> DoD#743
http://www.cskk.ezoshosting.com/cs/

If your new theorem can be stated with great simplicity, then there
will exist a pathological exception.    - Adrian Mathesis