| Section | Video Links |
|---|---|
| Observer Overview |    |
| Observer Use Case | |
| Python Set | |
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python ./observer/observer_concept.py
Observer id:2084220160272 received ('First Notification', [1, 2, 3])
Observer id:2084220160224 received ('First Notification', [1, 2, 3])
Observer id:2084220160272 received ('Second Notification', {'A': 1, 'B': 2, 'C': 3})... Refer to Book, pause Video Lectures or subscribe to Medium Membership to read textual content.
python ./observer/client.py
PieGraph, id:1
Drawing a Pie graph using data:[1, 2, 3]
BarGraph, id:2
Drawing a Bar graph using data:[1, 2, 3]
TableView, id:3
Drawing a Table view using data:[1, 2, 3]
PieGraph, id:1
Drawing a Pie graph using data:[4, 5, 6]
TableView, id:3
Drawing a Table view using data:[4, 5, 6]A Python Set is similar to a List. Except that the items in the Set are guaranteed to be unique, even if you try to add a duplicate. A set is a good choice for keeping a collection of observables, since the problem of duplicate observables is automatically handled.
A Set can be instantiated using the curly braces {} or set(), verses [] for a List and () for a Tuple. It is not the same as a Dictionary, which also uses {}, since the dictionary items are created as key:value pairs. ie {"a": 1, "b": 2, "c": 3}
PS> python
>>> items = {"yankee", "doodle", "dandy", "doodle"}
>>> items
{'yankee', 'doodle', 'dandy'}
>>> items.add("grandy")
>>> items
{'grandy', 'yankee', 'doodle', 'dandy'}
>>> items.remove("doodle")
>>> items
{'grandy', 'yankee', 'dandy'}Note, if instantiating an empty Set then use my_object = Set() rather than my_object = {} to reduce ambiguity with creating an empty Dictionary.
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