[Tutor] Behaviour of dictionaries and others when deleting?

Kent Johnson kent37 at tds.net
Tue May 22 03:17:19 CEST 2007

Bill Campbell wrote:
> Is the behaviour defined if one is processing a dictionary using
> iteritems, and delete items?
> for k, v in d.iteritems():
>     if somecondition(k, v): del d[k]
> Would this process all the original members of the dictionary?

This is not well-defined. You can use
   for k, v in d.items():

which creates a new list to hold the items and iterates that.

> I've always been leary of deleting items while processing things
> like this, keeping a list of keys to be deleted, then processing
> that list upon completion of the mail loop to delete the items
> from the original dictionary or database file.

I don't know about bsddb but for lists and dicts that is the right 
approach. You can also use a list comprehension to filter a list or dict.


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