foo.py

from __future__ import unicode_literals

import logging
import traceback

from prompt_toolkit.application import Application
from prompt_toolkit.buffer import Buffer, AcceptAction
from prompt_toolkit.interface import CommandLineInterface
from prompt_toolkit.key_binding.defaults import load_key_bindings
from prompt_toolkit.keys import Keys
from prompt_toolkit.layout.containers import HSplit, Window
from prompt_toolkit.layout.controls import BufferControl, FillControl, TokenListControl
from prompt_toolkit.layout.dimension import LayoutDimension as D
from prompt_toolkit.shortcuts import create_eventloop
from prompt_toolkit.token import Token

logging.basicConfig(filename='example.log', level=logging.DEBUG)
logging.info("Starting")

PROMPT = "PROMPT"
OUTPUT = "OUTPUT"

def get_titlebar_tokens(cli):
    return [
        (Token.Title, ' Hello world '),
        (Token.Title, ' (Press [Ctrl-Q] to quit.)'),
    ]

layout = HSplit([
    # The titlebar.
    Window(height=D.exact(1),
           content=TokenListControl(get_titlebar_tokens, align_center=True)),
    # fill line
    Window(height=D.exact(1), content=FillControl('-', token=Token.Line)),
    # content
    Window(content=BufferControl(buffer_name=OUTPUT)),
    # fill line
    Window(height=D.exact(1), content=FillControl('-', token=Token.Line)),
    # prompt
    Window(height=D.exact(1), content=BufferControl(buffer_name=PROMPT))
])

registry = load_key_bindings()

@registry.add_binding(Keys.ControlC, eager=True)
@registry.add_binding(Keys.ControlQ, eager=True)
def _(event):
    event.cli.set_return_value(None)

def _handler(cli, bfr):
    # save line
    text = bfr.text
    logging.debug("Got: %s", text)

    # reset line
    cli.buffers[PROMPT].reset(append_to_history=True)

    # append text to output window
    cli.buffers[OUTPUT].insert_line_below()
    cli.buffers[OUTPUT].insert_text(text)
    # TODO: limit backlog

buffers = {
    PROMPT: Buffer(
        is_multiline=False,
        accept_action=AcceptAction(handler=_handler)),
    OUTPUT: Buffer(is_multiline=True),
}

application = Application(
    layout=layout,
    buffers=buffers,
    key_bindings_registry=registry,
    use_alternate_screen=True,
    initial_focussed_buffer=PROMPT)

def run():
    eventloop = create_eventloop()

    try:
        cli = CommandLineInterface(application=application, eventloop=eventloop)
        cli.buffers[OUTPUT].text = "foo"
        cli.run()
    except Exception:
        logging.exception("failed")
        traceback.print_stack()
    finally:
        eventloop.close()

if __name__ == '__main__':
    run()