Understanding Event Functions and onStep in Python

What is the purpose of the onStep function?

• To handle mouse click events.

• To execute code once per second as defined by app.stepsPerSecond.

• To define the color of shapes.

• To initialize the application.

How many times does onStep run if app.stepsPerSecond is set to 1?

• Once per minute

• Once per second

• Twice per second

• Ten times per second

Your CMU CS Academy app has defined app.shapes as a python list.

Assume that the following local variables have appropriate values stored in them:

leftX, topY, wth, hgt

define an appropriate function that adds a new rectangle object to the list when the mouse is released.

The function definition for onMouseRelease is:

def onMouseRelease(mouseX, mouseY):

What data is accessible locally inside the function's implementation?

• mouseX, mouseY, mouseZ
• mouseX, mouseY
• mouseX, screenY
• mouseX, mouseY, buttonPressed

In python, which method is calledto add data to the end of a list?

• add
• insert
• extend
• append

In computer programming, what is the meaning of the term mutability?

• Mutability refers to the speed of a program's execution.
• Mutability is the process of creating new objects without modifying existing ones.
• Mutability is the ability of an object to be changed after its creation.
• Mutability means an object cannot be altered once created.

In your CMU CS Academy App, you have declared a python list named app.shapes.

Each time the onStep function triggers, you want to traverse the entire list of shapes. What code would your write to make this happen?

• while shape in app.shapes:
• for shape in app.shapes: # perform actions with shape
• foreach shape in app.shapes:
• for shape in app.shapes():

what does it mean to traverse a data structure such as a python list?

• To traverse a Python list means to delete elements from the list.
• Traversing a Python list involves sorting its elements.
• To traverse a Python list means to create a new list with the same elements.
• To traverse a Python list means to access each element in the list sequentially.

You are creating a painting app in CMU CS Academy using Python. You want your app to have the ability for the user to set different modes like draw, change, move, and delete for objects on the canvas.

You need to implement code in your onStep function to test which mode the user has selected. What code would you write given the 4 selections listed above?

• if mode == 'draw' # code to draw

  elif mode == 'change': # code to change

  elif mode == 'move': # code to move

  elif mode == 'delete': # code to delete

• if mode == 'draw': # code to draw elif mode == 'change': # code to change elif mode == 'move': # code to move elif mode == 'delete': # code to delete
• if mode == 'draw': # code to draw

  else mode == 'change': # code to change

  elif mode == 'move': # code to move elif mode == 'delete':

  # code to delete

• elif mode == 'draw': # code to draw

  elif mode == 'change': # code to change

  elif mode == 'move': # code to move

  elif mode == 'delete': # code to delete