Opened 4 months ago

Last modified 4 months ago

#1801 new defect

parley constructs an internally inconsistent input port

Reported by: Vasilij Schneidermann Owned by:
Priority: minor Milestone: someday
Component: extensions Version: 5.3.0
Keywords: parley port Cc: Christian Kellermann
Estimated difficulty: trivial


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))
#;5> (input-port? p)
#;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.

Change History (3)

comment:1 Changed 4 months ago by Vasilij Schneidermann

<mario-goulart> wasamasa: last time I checked, and 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.

comment:2 Changed 4 months ago by Vasilij Schneidermann

Estimated difficulty: mediumtrivial

comment:3 Changed 4 months ago by evhan

Perhaps C5 changed some port internals?

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

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.

Version 1, edited 4 months ago by evhan (previous) (next) (diff)
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