"Where is the Duck?"¶

This notebook illustrates how context-aware components can be developed in PyGX. In this example, Duck is a symbolic class which subscribes the on_topo_parent_change and on_topo_path_change events. Therefore, when the containing context of a Duck object is changed, it can respond to such changes.

In [ ]:

!pip install pygx

!pip install pygx

In [2]:

from typing import Any, Literal
import pygx as pg

from typing import Any, Literal import pygx as pg

In [3]:

class Venue(pg.Object, topo=True):
  occupied_by: Any = None

class Pool(Venue):
  size: Literal['small', 'large'] = 'small'
  color: Literal['green', 'blue', 'black'] = 'green'
  
  def __str__(self):
    return f'a {self.size} {self.color} pool'


class Cage(Venue):

  def __str__(self):
    return f'a small cold cage'

  def free(self):
    self.sym_rebind(occupied_by=None)

class Duck(pg.Object, topo=True):

  def on_topo_parent_change(self, old_parent, new_parent):
    super().on_topo_parent_change(old_parent, new_parent)
    def venue(parent):
      if isinstance(parent, Venue):
        return str(parent)
      return 'nowhere'
    print(f'I am moving from {venue(old_parent)} '
          f'to {venue(new_parent)}')
  
  def on_topo_path_change(self, old_path, new_path):
    super().on_topo_path_change(old_path, new_path)
    print(f'I am now identified by path "{new_path}"')

  def who_am_i(self):
    if isinstance(self.topo_parent, Pool):
      message = f'I am a happy duck swimming in {str(self.topo_parent)}.'
    elif isinstance(self.topo_parent, Cage):
      message = f'I am a sad duck wandering in {str(self.topo_parent)}.'
    else:
      message = f'I am just a duck.'
    print(message)

class Venue(pg.Object, topo=True): occupied_by: Any = None class Pool(Venue): size: Literal['small', 'large'] = 'small' color: Literal['green', 'blue', 'black'] = 'green' def __str__(self): return f'a {self.size} {self.color} pool' class Cage(Venue): def __str__(self): return f'a small cold cage' def free(self): self.sym_rebind(occupied_by=None) class Duck(pg.Object, topo=True): def on_topo_parent_change(self, old_parent, new_parent): super().on_topo_parent_change(old_parent, new_parent) def venue(parent): if isinstance(parent, Venue): return str(parent) return 'nowhere' print(f'I am moving from {venue(old_parent)} ' f'to {venue(new_parent)}') def on_topo_path_change(self, old_path, new_path): super().on_topo_path_change(old_path, new_path) print(f'I am now identified by path "{new_path}"') def who_am_i(self): if isinstance(self.topo_parent, Pool): message = f'I am a happy duck swimming in {str(self.topo_parent)}.' elif isinstance(self.topo_parent, Cage): message = f'I am a sad duck wandering in {str(self.topo_parent)}.' else: message = f'I am just a duck.' print(message)

In [4]:

duck = Duck()
duck.who_am_i()

duck = Duck() duck.who_am_i()

I am just a duck.

In [5]:

cage = Cage(occupied_by=duck)
duck.who_am_i()

cage = Cage(occupied_by=duck) duck.who_am_i()

I am now identified by path "occupied_by"
I am moving from nowhere to a small cold cage
I am a sad duck wandering in a small cold cage.

In [6]:

cage.free()

cage.free()

I am moving from a small cold cage to nowhere
I am now identified by path ""

In [7]:

pool = Pool(occupied_by=duck)
duck.who_am_i()

pool = Pool(occupied_by=duck) duck.who_am_i()

I am now identified by path "occupied_by"
I am moving from nowhere to a small green pool
I am a happy duck swimming in a small green pool.