Re: Pre-PEP: Dictionary accumulator methods

[Kent Johnson]

Bengt Richter wrote:
On Sat, 19 Mar 2005 01:24:57 GMT, "Raymond Hettinger" <[EMAIL PROTECTED]> wrote:
I would like to get everyone's thoughts on two new dictionary methods:
      def count(self, value, qty=1):
          try:
              self[key] += qty
          except KeyError:
              self[key] = qty
      def appendlist(self, key, *values):
          try:
              self[key].extend(values)
          except KeyError:
              self[key] = list(values)
How about an efficient duck-typing value-incrementer to replace both? E.g. 
functionally like:
 >>> class xdict(dict):
 ...     def valadd(self, key, incr=1):
 ...         try: self[key] = self[key] + type(self[key])(incr)
 ...         except KeyError: self[key] = incr
A big problem with this is that there are reasonable use cases for both
  d.count(key, <some integer>)
and
  d.appendlist(key, <some integer>)
Word counting is an obvious use for the first. Consolidating a list of key, value pairs where the 
values are ints requires the second.

Combining count() and appendlist() into one function eliminates the second 
possibility.
Kent
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