[Python-Dev] One obvious way to do interning [Was: Retrieve an arbitrary element from a set without removing it] (original) (raw)

Nick Coghlan ncoghlan at gmail.com
Mon Oct 26 22:50:56 CET 2009

Terry Reedy wrote:

Alexander Belopolsky wrote:

Terry Reedy wrote:

I had exactly the same idea, but did not post because it violates the general rule that mutators return None.

Is there such a rule? What about set/dict pop? The rule perhaps should be restated as 'Collection mutators return None or possible an item but not the collection.'

And to clarify the rationale for that guideline: it is to make it clear that the mutator is changing the container in place and not creating a new container object.

myset.pop() # No new container, returns popped object mylist.sort() # No new container, returns None sorted(mylist) # New container, so return it mystr.lower() # Creates new string, so return it

Cheers, Nick.

-- Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia

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