streams.py

class Streams(object):
    def _initialize_attributes(self):
        try:
            from IPython import get_ipython
        except ImportError:
            pass
        try:
            get_ipython()
        except NameError:
            self._OutStream = None
            self._IPythonIOStream = None
        else:
            from IPython import version_info
            ipython_major_version = version_info[0]

            try:
                from ipykernel.iostream import OutStream
                self._OutStream = OutStream
            except ImportError:
                try:
                    from IPython.zmq.iostream import OutStream
                    self._OutStream = OutStream
                except ImportError:
                    if ipython_major_version < 4:
                        try:
                            from IPython.kernel.zmq.iostream import OutStream
                            self._OutStream = OutStream
                        except ImportError:
                            self._OutStream = None
                    else:
                        self._OutStream = None


            if self.OutStream is not None:
                from IPython.utils import io as ipyio
                # On Windows in particular this is necessary, as the io.stdout stream
                # in IPython gets hooked up to some pyreadline magic to handle colors
                self._IPythonIOStream = ipyio.IOStream
            else:
                self._OutStream = None
                self._IPythonIOStream = None

            # On Windows, in IPython 2 the standard I/O streams will wrap
            # pyreadline.Console objects if pyreadline is available; this should
            # be considered a TTY
            try:
                from pyreadyline.console import Console as PyreadlineConsole
                self._PyreadlineConsole = PyreadlineConsole
            except ImportError:
                # Just define a dummy class
                class PyreadlineConsole(object): pass
                self._PyreadlineConsole = PyreadlineConsole
                
    @property
    def OutStream(self):
        try:
            return self._OutStream
        except AttributeError:
            self._initialize_attributes()
            return self._OutStream
                
    @property
    def IPythonIOStream(self):
        try:
            return self._IPythonIOStream
        except AttributeError:
            self._initialize_attributes()
            return self._IPythonIOStream
                
    @property
    def PyreadlineConsole(self):
        try:
            return self._PyreadlineConsole
        except AttributeError:
            self._initialize_attributes()
            return self._PyreadlineConsole
          
streams = Streams()  # global variable (Singleton)


# in the other functions just use:
streams.PyreadlineConsole
streams.OutStream
streams.IPythonIOStream