Npyscreen

Widget library and application framework built on top of ncurses. ^{Documentation]}

Three main types of object compose npyscreen applications: - Application objects manage forms and other classes - Form objects form the canvas upon which widgets are arrayed - Form general-purpose - FormMutt - Widget objects are individual controls - TitleText text entry - TitleSelectOne equivalent to radio buttons - TitleDateCombo allows picking of date on a small calendar

npyscreen.wrapper_basic is the main entry point

import npyscreen

def myFunction(*args):
  pass

if __name__ == '__main__':
  npyscreen.wrapper_basic(myFunction)
  print "Blink and you missed it!"

npyscreen.Form is equivalent to the Tk() object, which is typically instantiated as win in GUI frameworks.

F = npyscreen.Form(name='My Test Application')

Several important methods are key: - create() The standard constructor calls this method, which does nothing by default and is meant to be overriden in subclasses. Widgets are defined here.

npyscreen.FormMutt imitates a UI layout popularized by applications like mutt, irssi, and vim, with a title bar at the top, a command line at the bottom, and a status line directly above the command line.

ACTION_CONTROLLER can be defined in the FormMutt subclass as the name of a subclass of ActionControllerSimple. Commands for the application can be defined as callbacks in the create() method.

self.add_action(ident,call_back, True)

Callbacks are called with the following arguments:

call_back(command_line, control_widget_proxy, live=True)

class ActionControllerSearch(npyscreen.ActionControllerSimple):
    def create(self):
        self.add_action('^/.*', self.set_search, True)

    def set_search(self, command_line, widget_proxy, live):
        self.parent.value.set_filter(command_line[1:])
        self.parent.wMain.values = self.parent.value.get()
        self.parent.wMain.display()

class FmSearchActive(npyscreen.FormMuttActiveTraditional):
    ACTION_CONTROLLER = ActionControllerSearch

npyscreen.NPSAppManaged is the preferred superclass to support object-oriented implementation.

class MyApplication(npyscreen.NPSAppManaged):
  pass

Calling run() method of application object as main entry point. run() activates the default form, which should be given an id of MAIN

if __name__ == '__main__':
  TestApp = MyApplication().run()
  print "All objects, baby."

Using a try/except block to allow for well-mannered exit in case of KeyboardInterrupt (Ctrl+C)^GitHub

try:
  App().run()
except KeyboardInterrupt:
  sys.exit(0)

There are three methods for registering a Form object with a NPSAppManaged instance; - addForm() creates a new form and returns a weakref.proxy to it - addFormClass() register a class of Form rather than an instance - registerForm()

It continually displays the Form named by its NEXT_ACTIVE_FORM attribute. Use the afterEditing method to allow exiting.

class myEmployeeForm(npyscreen.Form):
  def afterEditing(self):
    self.parentApp.setNextForm(None)