affix_repy_network_api_wrapper.r2py

"""
affix_repy_network_api_wrapper.r2py

This implements a class to represent the original Repy network call 
definitions. It defines network calls like an Affix component (so 
another component can point its methods to ours) but raises 
AffixStackError's when its stack manipulation methods are called 
(as it is destined to sit immutably at the bottom of an Affix stack).

This design was chosen so that Affix components need not worry 
(i.e. special-case) whether or not the Repy API or further Affix 
components are below them.
"""

affix_exceptions = dy_import_module("affix_exceptions.r2py")
base_affix = dy_import_module("baseaffix.r2py")

class RepyNetworkAPIWrapper(base_affix.BaseAffix):
  def __init__(self, next_affix=None):
    """
    The constructor. Must not be called with a next_affix, as this 
    would imply we are not at the bottom of the Affix stack.
    """
    assert next_affix is None, "RepyNetworkAPIWrapper initialized with next_affix='" + str(next_affix) + "' (not None), implying it is not at the bottom of the Affix stack."

    # Save references to the Repy network API calls of the outer scope
    self.getmyip = getmyip
    self.gethostbyname = gethostbyname
    self.sendmessage = sendmessage
    self.listenformessage = listenformessage
    self.openconnection = openconnection
    self.listenforconnection = listenforconnection


  # Override BaseAffix's socket.* functions. (They use peek(), 
  # we don't allow that.)
  def socket_close(self, socket):
    return socket.close()


  def socket_send(self, socket, msg):
    return socket.send(msg)


  def socket_recv(self, socket, bytes):
    return socket.recv(bytes)


  def tcpserversocket_getconnection(self, tcpserversocket):
    return tcpserversocket.getconnection()


  def tcpserversocket_close(self, tcpserversocket):
    return tcpserversocket.close()


  def udpserversocket_getmessage(self, udpserversocket):
    return udpserversocket.getmessage()


  def udpserversocket_close(self, udpserversocket):
    return udpserversocket.close()


  # Raise errors when someone tries to modify the stack below us.
  def peek(self):
    raise affix_exceptions.AffixStackError("Cannot peek() past the bottom of the stack!")


  def pop(self):
    raise affix_exceptions.AffixStackError("Nothing left on the stack to pop() below me!")


  def push(self, new_affix_object):
    raise affix_exceptions.AffixStackError("Cannot push() " + str(new_affix_object) + 
        "to below the bottom of the stack!")

  def copy(self):
    """
    I don't believe it makes sense to create a new RepyNetworkAPIWrapper 
    object providing the same functionality as this one does....
    """
    return self


  def get_advertisement_string(self):
    """
    RepyNetworkAPIWrapper is implicitly there at the bottom of 
    the stack. We don't advertise.
    """
    return ""

  def __str__(self):
    return repr(self).replace(' instance at', '')