[Python-ideas] The non-obvious nature of str.join (was Re: sum(...) limitation)

[Wolfgang Maier]

On 11.08.2014 23:35, Ethan Furman wrote:
>
>> class Nasty:
>>      def __radd__(self, other):
>>          return other + "foo"
>>
>> "".join(["some", "strings", "and", "one", Nasty()])
>> sum(["some", "strings", "and", "one", Nasty()], "")
>

Interesting. So a slight variation enables sum-based string 
concatenation *right now*:

class ZeroAdditionProperty:
     def __add__(self, other):
         return other

nullstr = ZeroAdditionProperty()

sum(["some", "strings", "and", "one"], nullstr)

Wolfgang