From: Luke <lbayes@...>
Date: 2007-06-11T03:05:05+09:00
Subject: Re: Interacting with a long-lived external process from ruby?

OK - I figured it out.

The process I am interacting with has similar behavior to the irb
shell application.

What I didn't realize was that when the process writes to the stream
that I'm reading on, the prompt line does not include an EOL
character. This was blocking the read stream until either
write_stream.close or other output was forced.

Essentially, I just decorated my process and implemented a read method
as follows:

----------------8<-----------------

def read
  line = ''
  response = ''
  while(!r.eof?)
    char = r.getc.chr
    line += char
    if(line == '(fcsh)')
      response += "[PROMPT] #{line}"
      break
    end
    if(char == "\n")
      response += "[FCSH] #{line}"
      line = ''
    end
  end
  return response
end

---------------->8-----------------

IO.getc being the key component as it returns every byte that is
written to the stream, without regard for EOL characters.

This read method behaves similarly to the IO.read method except it
will return when the prompt is encountered.

Also -

As it turns out Open3.popen3 works just fine and is much simpler than
what I was using before.



Thanks,


Luke Bayes
http://www.asserttrue.com