[Python-ideas] set.add() return value

[Leonardo Santagada]

On Feb 17, 2009, at 12:14 AM, Raymond Hettinger wrote:

>>> As I mentioned in another post, this API is counterintuitive for
>>> anyone who is used to other languages where operations like
>>> set.add() always returns self and lets them write code like:
>>>
>>>    myset.add(x).add(y).add(z)
>>
>> Which language has that?
>
> I think there a several.
>
> Smalltalk comes to mind:
> '''
>        addAll: aCollection
>         Adds all the elements of 'aCollection' to the receiver,  
> answer aCollection
> '''
>
> Looks like Objective C takes the same approach:
> '''
> Method: IndexedCollection @keyword{-insertObject:} newObject  
> @keyword{atIndex:} (unsigned)index
> @deftypemethodx IndexedCollecting {} @keyword{-insertElement:}  
> (elt)newElement @keyword{atIndex:} (unsigned)index
> returns self.
> '''
>
> Also, Ruby uses the style of having mutating methods return self:
>
> '''
> arr.fill( anObject ) -> arr
> arr.fill( anObject, start [, length ] ) -> arr
> arr.fill( anObject, aRange ) -> arr
>
>
> hsh.update( anOtherHash ) -> hsh
>
> Adds the contents of anOtherHash to hsh, overwriting entries with  
> duplicate keys with those from anOtherHash.
>
>     h1 = { "a" => 100, "b" => 200 }
>     h2 = { "b" => 254, "c" => 300 }
>     h1.update(h2)  » {"a"=>100, "b"=>254, "c"=>300}
>
> '''
>
>
> I haven't checked other languages but am sure I've seen this style  
> show-up in a number of places.


JQuery also does this. Can I ask why python doesn't do it? Seems a  
more interesting change than returning a boolean.

--
Leonardo Santagada
santagada at gmail.com