Yup, same basic page; with a few asides: - still don't suspect it's a good idea to specify any particular encoding for scheme's required character-set. - still don¹t suspect it's a good idea to allow potentially non-portable characters to be used in identifier or comments. - still suspect it would be nice to be able to extend the concept of being able to specify hierarchical format/encoding port procedures. - and lastly, actually rather like your "titled:" argument syntax, makes reading and likely writing most code much easier and less error prone. > From: Per Bothner <xxxxxx@bothner.com> > Date: Fri, 13 Feb 2004 10:34:47 -0800 > To: bear <xxxxxx@sonic.net> > Cc: Paul Schlie <xxxxxx@comcast.net>, xxxxxx@srfi.schemers.org > Subject: Re: Encodings. > Resent-From: xxxxxx@srfi.schemers.org > Resent-Date: Fri, 13 Feb 2004 19:34:54 +0100 (NFT) > > bear wrote: > >> If there are multiple encodings/canonicalizations/etc in use >> on a system, let schemes on those systems implement multiple kinds of >> character ports. > > I don't think that's a good idea. > >> But it follows that there is NO WAY we should rely on I/O of >> characters through character ports to read or write a particular >> binary representation for "raw" data such as sound and image files. > > Does not follow. > > May I suggest the Kawa solution: > > You want to be able to specify character encoding when you open a > file, even if people mostly use a system dependent port. However > that encoding is specified is orthogoal to my suggestion: It can > be a parameter object or a option parameter: > > (define p (open-input-port "foo.txt" encoding: "ebcdic")) > > Add a special encoding for binary files: > > (define b (open-input-port "foo.bin" encoding: "binary")) > > A "binary" encoding maps the byte n to (integer->char b), > with no translations. > > Notice that a Windows or MacOS 8-bit system may do line-end > munging for the default encoding, but is not allowed to do > so for "binary". > >> The only reason programmers want to write characters that aren't in >> the "normal" encoding/canonicalization/etc, is when they need really >> close control of the exact format of I/O. But when you need control >> *that* close, you're not talking about a "character" port at all any >> more; you're talking about binary I/O. Rather than breaking the >> abstraction barrier on character ports, you need a different kind of >> port. We need binary ports that support operations like (read-bytes) >> and (write-bytes). > > Perhaps if you started from scratch, but my solution is more > compatible with existing Scheme code. > -- > --Per Bothner > xxxxxx@bothner.com http://per.bothner.com/ >