Formal comment #180 (defect)

Binary and string pseudo-transcoders should die
Reported by: 	John Cowan
Version:	5.92

Every R5.92RS port has a transcoder, which come in three flavors:
transcoders proper, which are attached to binary ports to make them
into textual ports; the binary transcoder, which does nothing except
stand in for a transcoder on a binary port; and the
implementation-defined transcoder provided for string ports. The
latter two flavors are not really transcoders, for they don't provide
any transcoding functions. I propose, therefore, that they be dropped.

The binary-transcoder procedure is no longer required, and #f is
returned by the port-transcoder procedure when applied to a binary
port or a string port.

In (I believe) all cases where the binary transcoder is referred to,
it can simply be dropped. The exception is the open-file-*-port
procedures, where a binary file can be opened only by explicitly
specifying the binary transcoder. This is inconsistent with other
kinds of port constructors, and I propose one of two resolutions:

A: If the transcoder is omitted, return a binary port. In order to
create a port with "native" transcoding, introduce a procedure
native-transcoder, which returns an implementation-dependent
transcoder.

B: Allow #f as an explicit argument to open-file-*-port procedures to
return a binary port.

I prefer A.


RESPONSE:

The recommendations of this comment (with option A) will be
incorporated into the next draft.