--- Michael Lazzaro <[EMAIL PROTECTED]> wrote: > > On Friday, November 1, 2002, at 08:02 AM, Mark J. Reed wrote: > >> When someone asks "what's the boolean type in Perl?" I'd rather > >> answer "bit" than "Perl doesn't have one", if for no other reason > >> than the latter answer will completely freak them out. :-) > > Why? Plenty of languages get along just fine without a Boolean > type. > > BASIC, C, LISP, Perl5, Python, TCL . . . > > In langs that do not recognize boolean as a type, the convention is > either to use an untyped thing or the "littlest possible" thing as a > boolean type. (The latter has more possibilities for efficiency, > obviously.) Let's look at a presumably common Perl6 construct:
Umm, this just ain't so. 'C' uses the int type as its basic boolean. You may be inclined to store the values in a char or a bitfield, but (a==b) is an int. > Since a "bit" can't even have properties (tho a "Bit" can), it really > is, for all practical purposes, a boolean value, and can be treated > as such. Fine and dandy, that's OK. 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? > 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: $.is_plugged_in = true but false; Maybe this should be an option only for female programmers? (Hoping my GF isn't reading this... :-) Frankly, I don't have a problem using a numeric value as a boolean. I'm used to it. If there were a boolean primitive type, I probably wouldn't use it correctly sometimes -- too much C/assembly work. But what's wrong with defining Boolean as a subtype of bit? On a vaguely-related note: It's possible to say $result = $value but true; Is it possible to use a variable in that expression? $result = $value but $bool; If so, does it dwim? How do I use it? $bool = "true"; ? $bool = true; ? $bool = (1 == 1); ? =Austin __________________________________________________ Do you Yahoo!? HotJobs - Search new jobs daily now http://hotjobs.yahoo.com/
