cpython/Lib/idlelib/run.py

import sys
import time
import socket
import rpc

def main():
    """Start the Python execution server in a subprocess

    In Idle, RPCServer is instantiated with handlerclass MyHandler, which
    inherits register/unregister methods from RPCHandler via the mix-in class
    SocketIO.

    When the RPCServer is instantiated, the TCPServer initialization creates an
    instance of run.MyHandler and calls its handle() method.  handle()
    instantiates a run.Executive, passing it a reference to the MyHandler
    object.  That reference is saved as an attribute of the Executive instance.
    The Executive methods have access to the reference and can pass it on to
    entities that they command (e.g. RemoteDebugger.Debugger.start_debugger()).
    The latter, in turn, can call MyHandler(SocketIO) register/unregister
    methods via the reference to register and unregister themselves.

    """
    port = 8833
    if sys.argv[1:]:
        port = int(sys.argv[1])
    sys.argv[:] = [""]
    addr = ("localhost", port)
    for i in range(6):
        time.sleep(i)
        try:
            svr = rpc.RPCServer(addr, MyHandler)
            break
        except socket.error, err:
            if i < 3:
                print>>sys.__stderr__, ".. ",
            else:
                print>>sys.__stderr__,"\nPython subprocess socket error: "\
                                              + err[1] + ", retrying...."
    else:
        print>>sys.__stderr__, "\nConnection to Idle failed, exiting."
        sys.exit()
    svr.handle_request() # A single request only

class MyHandler(rpc.RPCHandler):

    def handle(self):
        executive = Executive(self)
        self.register("exec", executive)
        sys.stdin = self.get_remote_proxy("stdin")
        sys.stdout = self.get_remote_proxy("stdout")
        sys.stderr = self.get_remote_proxy("stderr")
        rpc.RPCHandler.handle(self)

class Executive:

    def __init__(self, rpchandler):
        self.rpchandler = rpchandler
        import __main__
        self.locals = __main__.__dict__

    def runcode(self, code):
        exec code in self.locals

    def start_the_debugger(self, gui_adap_oid):
        import RemoteDebugger
        return RemoteDebugger.start_debugger(self.rpchandler, gui_adap_oid)

    def stop_the_debugger(self, idb_adap_oid):
        "Unregister the Idb Adapter.  Link objects and Idb then subject to GC"
        self.rpchandler.unregister(idb_adap_oid)

    def stackviewer(self, flist_oid=None):
        if not hasattr(sys, "last_traceback"):
            return None
        flist = None
        if flist_oid is not None:
            flist = self.rpchandler.get_remote_proxy(flist_oid)
        import RemoteObjectBrowser
        import StackViewer
        tb = sys.last_traceback
        while tb and tb.tb_frame.f_globals["__name__"] in ["rpc", "run"]:
            tb = tb.tb_next
        item = StackViewer.StackTreeItem(flist, tb)
        return RemoteObjectBrowser.remote_object_tree_item(item)