Python ฟังก์ชัน __str__()

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def __str__(self):
        return f"{self.name}, {self.age} years old"

# สร้างวัตถุจากคลาส Person
person = Person("John", 30)

# การเรียกใช้ __str__()
print(person)  # Output: John, 30 years old

class Book:
    def __init__(self, title, author, pages):
        self.title = title
        self.author = author
        self.pages = pages

    def __str__(self):
        return f"'{self.title}' by {self.author}, {self.pages} pages"

# สร้างวัตถุจากคลาส Book
book = Book("1984", "George Orwell", 328)

print(book)  # Output: '1984' by George Orwell, 328 pages

class Animal:
    def __init__(self, name):
        self.name = name

    def __str__(self):
        return f"Animal: {self.name}"

class Dog(Animal):
    def __init__(self, name, breed):
        super().__init__(name)
        self.breed = breed

    def __str__(self):
        return f"Dog: {self.name}, Breed: {self.breed}"

# สร้างวัตถุจากคลาส Dog
dog = Dog("Buddy", "Golden Retriever")

print(dog)  # Output: Dog: Buddy, Breed: Golden Retriever

class Product:
    def __init__(self, name, price):
        self.name = name
        self.price = price

    def __str__(self):
        return f"{self.name} (${self.price})"

# สร้างลิสต์ของวัตถุ
products = [Product("Laptop", 1000), Product("Phone", 500), Product("Tablet", 300)]

# ใช้ลูปเพื่อแสดงผลวัตถุ
for product in products:
    print(product)
    
# Output:
# Laptop ($1000)
# Phone ($500)
# Tablet ($300)

class Transaction:
    def __init__(self, transaction_id, amount, status):
        self.transaction_id = transaction_id
        self.amount = amount
        self.status = status

    def __str__(self):
        return f"Transaction ID: {self.transaction_id}, Amount: {self.amount}, Status: {self.status}"

# สร้างวัตถุจากคลาส Transaction
transaction = Transaction(12345, 250.75, "Pending")

# การแสดงผลเพื่อช่วย Debug
print(transaction)  # Output: Transaction ID: 12345, Amount: 250.75, Status: Pending

import json

class User:
    def __init__(self, username, email):
        self.username = username
        self.email = email

    def __str__(self):
        return json.dumps({"username": self.username, "email": self.email})

# สร้างวัตถุจากคลาส User
user = User("john_doe", "[email protected]")

# แสดงผลในรูปแบบ JSON
print(user)  # Output: {"username": "john_doe", "email": "[email protected]"}