Behavioral patterns (Observer, Strategy, Command) in Software Engineering - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the Observer interface method name.

Software Engineering

class Observer:
    def [1](self, message):
        pass

Drag options to blanks, or click blank then click option'

Aexecute

Bhandle

Cnotify

Dupdate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'notify' instead of 'update' as the method name.

The Observer pattern requires an update method that observers implement to receive notifications.

2fill in blank

medium

Complete the code to select the correct Strategy interface method name.

Software Engineering

class Strategy:
    def [1](self, data):
        pass

Drag options to blanks, or click blank then click option'

Aexecute

Brun

Cupdate

Dnotify

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing with 'run' or 'update' which are less common.

In the Strategy pattern, the method that performs the algorithm is usually called execute.

3fill in blank

hard

Fix the error in the Command pattern method name for executing a command.

Software Engineering

class Command:
    def [1](self):
        pass

Drag options to blanks, or click blank then click option'

Aupdate

Brun

Cexecute

Dnotify

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'run' or 'update' which are not standard for Command pattern.

The Command pattern uses an execute method to perform the action.

4fill in blank

hard

Fill both blanks to complete the Observer pattern subject notifying observers.

Software Engineering

class Subject:
    def __init__(self):
        self.observers = []

    def attach(self, observer):
        self.observers.append(observer)

    def notify_observers(self, message):
        for observer in self.observers:
            observer.[1](message)

subject = Subject()
subject.[2](observer_instance)

Drag options to blanks, or click blank then click option'

Aupdate

Bnotify

Cattach

Dexecute

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'notify' instead of 'update' for observer method.

Using 'notify' instead of 'attach' to add observers.

The Subject calls update on each observer to notify them. To add an observer, it uses attach.

5fill in blank

hard

Fill all three blanks to complete a Strategy pattern example selecting and running a strategy.

Software Engineering

class Context:
    def __init__(self, strategy):
        self.strategy = strategy

    def set_strategy(self, [1]):
        self.strategy = [2]

    def execute_strategy(self, data):
        return self.strategy.[3](data)

Drag options to blanks, or click blank then click option'

Astrategy

Cexecute

Dupdate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'update' instead of 'execute' for the strategy method.

The Context sets a new strategy using the parameter named 'strategy'. It then calls the strategy's execute method to run the algorithm.