Hello! >> 1. The notion of a “binary-friendly” ISO-8859-1 encoding? It’s >> actually mostly gone with the iconv change, since every textual >> access goes through iconv. For binary accesses, the right API is >> (rnrs io ports) or similar. > > An equivalent question is if you care about backward compatibility of > legacy ports. Legacy ports returned strings and were once the only option.
You mean if there’s legacy code using a port of unspecified encoding to read binary data, right? The iconv change doesn’t break it on GNU/Linux: --8<---------------cut here---------------start------------->8--- scheme@(guile-user)> (define p (open-bytevector-input-port #vu8(0 1 2 3 255 128))) scheme@(guile-user)> (set-port-encoding! p "ISO-8859-1") scheme@(guile-user)> (read-char p) $14 = #\nul scheme@(guile-user)> (read-char p) $15 = #\soh scheme@(guile-user)> (read-char p) $16 = #\stx scheme@(guile-user)> (read-char p) $17 = #\etx scheme@(guile-user)> (read-char p) $18 = #\ÿ scheme@(guile-user)> (read-char p) $19 = #\200 scheme@(guile-user)> (read-char p) $20 = #<eof> --8<---------------cut here---------------end--------------->8--- However, an iconv implementation may be free to choke on anything that’s not strictly Latin-1 per <https://secure.wikimedia.org/wikipedia/en/wiki/ISO-8859-1#Codepage_layout>, e.g., everything but “ÿ” in the example above, but that seems highly unlikely. Anyway, as soon as you use a non-Latin-1 locale, ports get opened under that locale’s encoding, which practically makes it impossible to do binary I/O on the ports. >> 2. The #f <=> "ISO-8859-1" equivalence for ‘port-encoding’ and >> ‘set-port-encoding!’. Likewise, commit >> d9544bf012b6e343c80b76bd5761b1583cc106a3 makes ‘port-encoding’ >> always return a string and pt->encoding always be non-NULL. > > Is the cost of doing the various string comparisons of port-encoding > strings negligible? It was put in as a (premature) optimization. The new code keeps open iconv conversion descriptors for each port and re-uses them; the only use of pt->encoding is when opening those CDs. Thanks, Ludo’.