216 Calling methods

1. What is the generic syntax for calling a method on an object in Python?

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The syntax is .(). For example: oLightSwitch.turnOn().

1. Why must the class definition appear before any code that creates objects from it?

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Because Python needs to know what the class is (its structure and methods) before it can create objects (instances) from it. If the class were undefined at the time of instantiation, Python would raise an error.

1. What happens to oLightSwitch1.switchIsOn and oLightSwitch2.switchIsOn in the following code?

oLightSwitch1 = LightSwitch()
oLightSwitch2 = LightSwitch()
oLightSwitch1.turnOn()
oLightSwitch1.show()
oLightSwitch2.show()

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oLightSwitch1.switchIsOn becomes True after turnOn() is called, so oLightSwitch1.show() prints True. oLightSwitch2.switchIsOn remains False, so oLightSwitch2.show() prints False.

1. How does the use of instance variables in the LightSwitch class help when working with multiple objects?

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Each object (instance) has its own separate copy of the instance variables (like switchIsOn). This means the state of one object does not affect the state of another, making the program easier to manage and scale.

1. Write Python code to create two LightSwitch objects. Turn the first one on and leave the second one off. Print the state of both switches.

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oLightSwitch2 = LightSwitch()
oLightSwitch2 = LightSwitch()
oLightSwitch1.turnOn()
oLightSwitch1.show()
oLightSwitch2.show()

1. Why is it better to use objects with instance variables instead of using multiple global variables in larger projects?

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Objects with instance variables keep data and behaviour bundled together, reducing the risk of unintended interactions and making the code more modular, scalable, and easier to maintain. This is especially important in larger projects with many entities.