# channel.py
#
# A minimal object that implements a message channel over a pair
# of file descriptors (like a pipe)

import cPickle as pickle

class Channel(object):
    def __init__(self,out_f,in_f):
        self.out_f = out_f
        self.in_f = in_f
    def send(self,item):
        pickle.dump(item,self.out_f)
        self.out_f.flush()
    def recv(self):
        return pickle.load(self.in_f)

# Example of using the channel
if __name__ == '__main__':
    import subprocess
    p = subprocess.Popen(['python','child.py'],
                         stdin=subprocess.PIPE,
                         stdout=subprocess.PIPE)
    ch = Channel(p.stdin,p.stdout)
    ch.send("Hello World")
    print ch.recv()
    ch.send(42)
    print ch.recv()
    ch.send([1,2,3,4,5])
    print ch.recv()