[Grok-dev] Iterativly emptying a grok.container shows weird behavior

[Tres Seaver]

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Brandon Craig Rhodes wrote:
> Tres Seaver <tseaver at palladion.com> writes:
> 
>> Dr. Volker Jaenisch wrote:
> 
>>> ME VOLKER ASK BUG OR FEATURE? VOLKER NO LIKE BUG! VOLKER NO LIKE FEATURE!
> 
> Hilarious!  What a fun mailing list I've joined.  Volker is my
> favorite so far.
> 
>> Volker might like it more if the container had 100,000 items in it,
>> where iterating over the keys rather than getting them all back as a
>> list would be much faster.
> 
> Nonsense.  If Volker is unhappy getting a huge list from .keys(), he
> can call .iterkeys() instead.  Please review the Python interface for
> mapping types; it says explicitly that .keys() returns:
> 
>    "a copy of a's list of keys"
> 
> They key word there is "copy" - the caller has a right to expect that
> the sequence of keys he has been returned is a "copy", that is, an
> object that now stands independent of the dictionary-like object that
> generated it.
> 
> Making the decision to turn .keys() into .iterkeys() unilaterally
> destroys the whole point of dictionary-like objects supporting both
> methods, and, as Volker rightly complains, it breaks many common
> Python idioms for working with dictionaries.

OOBTree *long* predates the introduction of 'iterkeys' into Python's
standard libraries[1], and is widely used in applications where the
scalability of 'keys' matters a *lot*:  creating the copy of the keys
can involve not only allocating memory for it, but also loading lots of
bucket objects from the ZODB which would otherwise remain dormant.

[1] http://www.python.org/download/releases/2.2.3/NEWS.txt



Tres.
- --
===================================================================
Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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