Pre-PEP: Dictionary accumulator methods

[El Pitonero]

Dan Sommers wrote:
> On Sat, 19 Mar 2005 01:24:57 GMT,
> "Raymond Hettinger" <vze4rx4y at verizon.net> wrote:
>
> > The proposed names could possibly be improved (perhaps tally() is
more
> > active and clear than count()).
>
> Curious that in this lengthy discussion, a method name of
"accumulate"
> never came up.  I'm not sure how to separate the two cases
(accumulating
> scalars vs. accumulating a list), though.

Is it even necessary to use a method name?

import copy
class safedict(dict):
    def __init__(self, default=None):
        self.default = default
    def __getitem__(self, key):
        try:
            return dict.__getitem__(self, key)
        except KeyError:
            return copy.copy(self.default)


x = safedict(0)
x[3] += 1
y = safedict([]) 
y[5] += range(3) 
print x, y 
print x[123], y[234]