A class is a blueprint that describes what data and behavior a type of object should have. An object is one specific instance created from that class.

Think of a class as a miner model specification. The specification can define fields such as a miner’s name, hashrate, and temperature. Each physical miner is a separate object with its own values. Python classes let us model that relationship directly in code.

Why classes matter

Functions organize reusable actions, while classes organize related data and actions together. Review OSPython.001: Functions, Parameters, and Return Values if function definitions still feel unfamiliar.

A dictionary can hold one miner’s values, as introduced in OSPython.003: Dictionaries and Key-Value Data. A class goes further: it gives every miner object a consistent structure and can include methods that operate on its data.

Create your first class

class Miner:
    def __init__(self, name, hash_rate):
        self.name = name
        self.hash_rate = hash_rate

The keyword class begins a class definition. By convention, class names use capitalized words, so this class is named Miner.

The __init__() method runs when a new object is created. It receives the starting values and stores them on that object. The name self refers to the particular object currently being created or used.

Create an object

miner_1 = Miner("Satoshi", 100)

print(miner_1.name)
print(miner_1.hash_rate)

miner_1 is an object—also called an instance—of the Miner class. Its name attribute contains "Satoshi", and its hash_rate attribute contains 100.

Add behavior with a method

A method is a function defined inside a class. It describes an action an object can perform.

class Miner:
    def __init__(self, name, hash_rate):
        self.name = name
        self.hash_rate = hash_rate

    def status(self):
        return f"{self.name}: {self.hash_rate} TH/s"

Call the method through the object:

miner_1 = Miner("Satoshi", 100)
print(miner_1.status())

The output is:

Satoshi: 100 TH/s

One class, multiple objects

miner_1 = Miner("Satoshi", 100)
miner_2 = Miner("Hal", 200)

print(miner_1.status())
print(miner_2.status())

Both objects follow the same Miner blueprint, but each object stores its own attributes. Changing miner_1.hash_rate does not automatically change miner_2.hash_rate.

Attributes, methods, classes, and objects

• Class: the blueprint, such as Miner.
• Object or instance: one item created from the blueprint, such as miner_1.
• Attribute: data stored on an object, such as name or hash_rate.
• Method: behavior defined by the class, such as status().
• self: the current object receiving a method call.

Common beginner mistakes

• Forgetting self as the first parameter of an instance method.
• Writing name = name instead of self.name = name.
• Calling an instance method on the class without creating an object first.
• Using inconsistent indentation inside the class body.
• Confusing the class name Miner with the object variable miner_1.

Practice: build a temperature alarm

Create a Miner class with name and temperature attributes. Add a method named needs_attention() that returns True when the temperature is greater than 80.

class Miner:
    def __init__(self, name, temperature):
        self.name = name
        self.temperature = temperature

    def needs_attention(self):
        return self.temperature > 80

Create two miner objects with different temperatures. Print each miner’s name and the result of needs_attention(). Then place the class in its own module or package using the structure from OSPython.011: Packages and __init__.py.

Quick knowledge check

1. What is the difference between a class and an object?
2. When does __init__() run?
3. What does self represent?
4. What is the difference between an attribute and a method?

Check your answers

1. A class is a blueprint; an object is one instance created from that blueprint.
2. It runs when a new object is created from the class.
3. The particular object currently being created or used.
4. An attribute stores data; a method defines behavior.

Key takeaway

Use a class when several objects need the same structure and behavior. The class defines the pattern; each object keeps its own state.

Reference

Continue with the official Python tutorial on classes.