obj-observe 0.1.5

Transparent Object Change Observers for Python objects and dicts

obj-observe

obj-observe is a simple, zero-dependency Python library for observing changes on object attributes and dictionary keys.

Installation

pip install obj-observe

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Example

from obj_observe import observe

class Player:
    def __init__(self):
        self.hp = 100

p = Player()

@observe(p, "hp")
def on_hp_change(old, new):
    print(f"HP changed: {old} -> {new}")

p.hp = 50

Core Functions

observe(obj, attr, callback=None)

This is the main function for attaching an observer to an attribute or key.

• As a Decorator:

  from obj_observe import observe
  
  class Player:
      def __init__(self, hp):
          self.hp = hp
  
  p = Player(100)
  
  @observe(p, 'hp')
  def on_hp_change(old_value, new_value):
      print(f"HP changed from {old_value} to {new_value}")
  
  p.hp = 150  # Prints: HP changed from 100 to 150
  

• With a Callback Function:

  def hp_watcher(old, new):
      print(f"HP was {old}, now it is {new}")
  
  observe(p, 'hp', hp_watcher)
  
  p.hp = 50 # Prints: HP was 150, now it is 50
  

• Observing Dictionary Keys:

  When observing a dictionary, observe returns an ObservableDict. You must use this new object to track changes.

  my_dict = {'status': 'idle'}
  
  def on_status_change(old, new):
      print(f"Status changed from '{old}' to '{new}'")
  
  my_dict = observe(my_dict, 'status', on_status_change)
  
  my_dict['status'] = 'running' # Prints: Status changed from 'idle' to 'running'
  

remove_observers(obj, attr=None)

Detaches observers from an object.

• Remove Observers from a Specific Attribute:

  remove_observers(p, 'hp')
  p.hp = 0 # No notification will be sent
  

• Remove All Observers from an Object:

  remove_observers(p)
  

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License

MIT