[rfc] UIFactory.is_interactive()

[Gordon Tyler]

Andrew Bennetts wrote:
>> This somewhat violates "don't look before you leap" but it's probably
>> worthwhile to avoid thinking about interactive stuff before you do it.
> 
> Maybe a less LBYL solution would be:
> 
>     if not ui_factory.get_boolean("really delete everything?", default=True):
>         return
>     delete_everything()
> 
> Although perhaps “default choice” is not precisely the same concept as “choice
> to take when non-interactive”, it's probably close enough.

If the parameter was made non-optional, then developers would be forced 
to think about how to handle the non-interactive case, which I think 
would be good for the overall behaviour of bzr in non-interactive 
situations.

Ciao,
Gordon