On Sat, Nov 02, 2002 at 07:07:43AM -0800, Austin Hastings wrote:
> I don't recall the terminology, but I believe that "0 but true" is a
> value with a "fillintheblank" (attribute?). What happens when you stick
> "0 but true" into a bit?
$z = 0 but true;
my bit $x = $z; # $x == 0
my bit $x = ?$z; # $x == 1
my bit $x = true $z; # $x == 1
I'm not even particularly upset by this:
my bool $x = $z; # $x == 1
But the moment anyone says
my bool $true = 1;
if x(1,2,3) == $true {...}
they're just asking for a world of hurt. I am overstating the case
when I say there's no boolean type in Perl. What I really mean is that
there is no such thing as a single true "true" value.
> > So what is the "official" way to efficiently store the result of a
> > boolean expression, for example? If not as a "bit", then what?
>
> The boolean-ness is a property of the evaluation of a value: if ($a)
> ....
>
> If the $a value has a 'but false' or 'but true' then that wins. If the
> $a value is a number, then 0 is false and everything else is true. If
> the value is a string, then ..yada yada yada..
>
> > If anything, I would suggest a primitive type, "bool", that has no
> > promoted type "Bool". It can just be a placeholder -- a "bit" alias
>
> Of course, a "bool" type would imply true/false values in the language.
> And THAT, in turn, implies that it's possible to say:
>
I don't mind a bool type. But you'll notice I've grabbed the keyword true()
to be a unary function. It will not default to "true". Perhaps it should
default to "undef". :-)
> $.is_plugged_in = true but false;
So that probably won't even parse.
Larry
