parley constructs an internally inconsistent input port

[Vasilij Schneidermann]

The parley egg still hasn't been ported successfully to C5. Most of the steps are done already (egg file, imports, tests), but interactive usage fails:

#;2> (define p (let ((old (current-input-port))) (make-parley-port old)))
#;3> p
#<port "(parley)">
#;4> (input-port? (current-input-port))
#t
#;5> (input-port? p)
#t
#;6> (current-input-port p)

Error: (current-input-port) bad argument type - not a port of the correct type: #<port "(parley)">

        Call history:

        <syntax>          (current-input-port p)
        <eval>    (current-input-port p)        <--

Looking at the code performing checks, it seems that the I/O direction slot is checked whether it's an input one. Both input-port? and current-input-port seem to look at the same slot, but arrive to different conclusions. Perhaps C5 changed some port internals?

One way of side-stepping this would be to avoid low-level port construction, but this might break C4 compatibility completely.

[Vasilij Schneidermann]

<mario-goulart> wasamasa: last time I checked, ​http://parenteses.org/mario/misc/parley-patches/0001-CHICKEN-5-support.patch and ​http://parenteses.org/mario/misc/parley-patches/0002-Adapt-Kooda-s-change-on-top-of-mine.patch were enough to make parley work.

I've confirmed the above two patches do the trick on an unmodified copy of parley-0.9.4. Therefore they can be used as is by the egg author to port it to C5. Feel free to close once it's been released.

[evhan]

Perhaps C5 changed some port internals?

It did, the direction slot changed from a boolean to a bitmap.

For code that is rummaging around inside a port's internals, if you want to know whether a port is open for input, you can check the first slot of the port for {{0x1}} (or {{0x2}} for output).

Not sure if that helps, just for the record.