Daniel Ruoso wrote:
> Hmm... I think that takes the discussion to another level, and the
> question is:
>
> "what does a capture returns when coerced to a context it doesn't
> provide a value for?"
>
> The easy answer would be undef, empty array and empty hash, but that
> doesn't DWIM at all.
>
> The hard answer is DWIM, and that can be:
>
> 1) in item context, without an invocant
> a) if only one positional argument, return it
> b) if only one named argument, return it as a pair
> c) if several positional args, but no named args,
> return an array
> d) if several named args, but no positional args,
> return a hash
> e) if no args at all, return undefined Object
> f) return itself otherwise
> 2) in list context, without positional arguments
> a) if one or more named arguments,
> return a list of pairs
> b) return an empty list otherwise
> 3) in hash context, without named arguments
> a) if there are positional arguments,
> return a hash taking key,value.
> if an odd number of positional arguments,
> last key has an undef Object as the
> value and issue a warning.
> b) return an empty hash otherwise
Elaborate further to account for the possibility of an invocant. For
example, if you have a capture object with just an invocant and you're
in list context, should it return the invocant as a one-item list, or
should it return an empty list? Should hash context of the same
capture object give you a single Pair with an undef value and a a
warning, or should it give you an empty hash?
I don't mind the dwimmery here, even though that means that you can't
be certain that (e.g.) 'list $x' will return the positional parameters
in capture object $x. If you want to be certain that you're getting
the positional parameters and nothing else, you can say '$x.[]'; if
you want to be certain that you're getting the named parameters, you
can say '$x.{}'. The only thing lost is the ability to ensure that
you're getting the invocant; and it wouldn't be too hard to define,
say, a postfix:<_> operator for the Capture object that does so:
item($x) # Dwimmey use of item context.
list($x) # Dwimmey use of list context.
hash($x) # Dwimmey use of hash context.
$x._ # the Capture object's invocant, as an item.
$x.[] # the Capture object's positional parameters, as a list.
$x.{} # the Capture object's named parameters, as a hash.
--
Jonathan "Dataweaver" Lang
