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Re: [Scheme-reports] Bidirectional ports and port-open?
On 07/01/2012 05:01 PM, John Cowan wrote:
> Per Bothner scripsit:
>> An true bi-directional port is one where you can read a "record",
>> modify it, and write it back. If the port is seekable, the input
>> and output positions are tied.
> I don't see how these can both be true unless the port is indeed
> seekable. If I read, modify, and then write, the write goes after the
> point read from unless I first seek back to before the read.
There can be an API that supports read-modify-write. But that again
would require non-standard extensions. A true bi-directional port
is indeed likely to be seekable, like Java's RandomAccessFile.
Regardless, I contend the concept of a port where "it is useful to close
the input and output sides separately" is bogus. What people are really
talking about is a "connection" (for example a socket object) which is a
different kind of object that has two *separate* ports, usually in addition
to other state.
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