Pre-PEP: Dictionary accumulator methods

[Brian van den Broek]

Kent Johnson said unto the world upon 2005-03-19 07:19:
> Brian van den Broek wrote:
> 
>> Raymond Hettinger said unto the world upon 2005-03-18 20:24:
>>
>>> I would like to get everyone's thoughts on two new dictionary methods:
>>>
>>>         def appendlist(self, key, *values):
>>>             try:
>>>                 self[key].extend(values)
>>>             except KeyError:
>>>                 self[key] = list(values)
>>>
>> For appendlist, I would have expected
>>
>> def appendlist(self, key, sequence):
>>     try:
>>         self[key].extend(sequence)
>>     except KeyError:
>>         self[key] = list(sequence)
> 
> 
> The original proposal reads better at the point of call when values is a 
> single item. In my experience this will be the typical usage:
>   d.appendlist(key, 'some value')
> 
> as opposed to your proposal which has to be written
>   d.appendlist(key, ['some value'])
> 
> The original allows values to be a sequence using
>   d.appendlist(key, *value_list)
> 
> Kent

Right. I did try the alternatives out and get the issue you point to.

But:

1) In my own code, cases where I'd use the proposed appendlist method 
are typically cases where I'd want to add multiple items that have 
already been collected in a sequence. But, since I've little coding 
under my belt, I concede that considerations drawn from my experience 
are not terribly probative. :-)

2) Much more important, IMHO, is that the method name `appendlist' 
really does suggest it's a list that will be appended. Hence my stated 
expectation. While it would make the method name longer, given the 
original interface Raymond posted, I would find appendtolist more 
transparent.

out-of-my-depth-ly y'rs,

Brian vdB