Done: https://www.assembla.com/spaces/clojure/tickets/284-cannot-cast-0xff-to-a-byte-(fails-out-of-range-check)
On Mar 24, 10:57 am, "Mark J. Reed" <markjr...@gmail.com> wrote: > On Tue, Mar 23, 2010 at 8:19 PM, Raph <mart...@gmail.com> wrote: > > (My opinion, anyway.I think a byte should be 8 bits and I should be able to > > use all of them.) > > Er, it is, and you can. A Java byte still gives you all 8 bits' worth > of 256 different possible values; the interpretation of those values > is all that differs here. Whereas C lets you pick between signed and > unsigned (with the default unfortunately not always well-defined), > Java gives you no choice but to use the signed interpretation. But > you still get to use all 8 bits of the byte; it's just that the > numbers mapped to [128, 255] in unsigned interpretations map to > [-128,-1] instead. > > The dissonance here comes from the fact that there's no real tradition > of negative hexadecimal numbers in programming. We've typically used > the hexadecimal form of the unsigned integer interpretation to > represent the corresponding bit patterns no matter how they're being > used in a given program or context. So anyone experienced with > manipulating things at the bit level comes in expecting things like > (byte 0xff) to just work, and is surprised when they don't. > > Still, the nice thing about Clojure vs Java is it's not hard to write a fix: > > (defmacro unsigned-byte [bval] (byte (if (> bval 127) (- bval 256) bval))) > > Or call it (ubyte) for less wordiness... > > -- > Mark J. Reed <markjr...@gmail.com> -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en To unsubscribe from this group, send email to clojure+unsubscribegooglegroups.com or reply to this email with the words "REMOVE ME" as the subject.
