ReactCHALLENGES

3. Instance attributes

An instance attribute is data stored on one specific object. You create it inside a method, usually __init__, with self.attribute = value:

  • self is the instance.
  • self.name is an attribute of that instance; name on the right is the parameter.
  • Every instance created by Dog(...) gets its own name.

From outside the class you read an attribute with a dot: object.attribute.

You can update an existing attribute or add a new one after the object exists:

Attributes belong to the instance, not to the class: changing dog.name does not affect another dog.

Coming from JavaScript? self.name = name is this.name = name, and dog.name works the same. There are no private fields here: every attribute is readable and writable from outside.

#01

Store one attribute

Inside __init__, store the name parameter as an attribute named name on the instance. Define Dog with __init__(self, name), create dog = Dog("Rex"), and print the attribute dog.name.

Print exactly:

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#02

Store two attributes

Define Point with __init__(self, x, y) and store both values as attributes with the same names. Create point = Point(1, 2), then print point.x and point.y, one per line.

Print exactly:

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#03

Two instances, two values

Define Dog with __init__(self, name) that stores self.name. Create first = Dog("Rex") and second = Dog("Luna"). Print first.name, then second.name.

Each instance keeps its own name; creating the second dog does not overwrite the first one.

Print exactly:

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#04

Update an attribute

Define Dog with __init__(self, name) that stores self.name. Create dog = Dog("Rex"), then change its name attribute to "Max" after creation. Print the attribute.

The __init__ still receives a name for new dogs; only this instance was updated.

Print exactly:

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#05

Add a new attribute

Define Dog with __init__(self, name) that stores self.name. Create dog = Dog("Rex"), then add an attribute named age with the value 3 after creation. Print dog.age.

Print exactly:

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