subscripting Python 3 dicts/getting the only value in a Python 3 dict

[Peter Otten]

Ian Kelly wrote:

> On Tue, Jan 12, 2016 at 10:12 AM, Terry Reedy <tjreedy at udel.edu> wrote:
>> Using the values views at intended (as an iterable):
>>
>>>>> dv = d.values()
>>>>> next(iter(dv))
>> 1
> 
> Good coding practice also dictates that whenever next is called, the
> potential StopIteration exception must be caught unless it is clearly
> intended to be propagated up to some generator. 

Even then you should be prepared for

https://docs.python.org/dev/whatsnew/3.5.html#pep-479-change-stopiteration-handling-inside-generators

> So more fully, this
> should be something like:
> 
> dv = iter(d.values())
> try:
>     next(dv)
> except StopIteration:
>     raise IndexError("d is empty")
> 
> At which point it may be desirable to extract that into a utility
> function.