# Python’s classes are used to group data together to form records.
# Here’s how you define a class and create instances of it.

class Person:
    def __init__(self, name, age=0):
        self.name = name
        self.age = age

# new_person constructs a new Person instance with the given name.
def new_person(name):
    # In Python, you typically return the instance directly.
    p = Person(name)
    p.age = 42
    return p

def main():
    # This syntax creates a new instance of a class.
    print(Person("Bob", 20))

    # You can specify the fields when initializing a class.
    print(Person(name="Alice", age=30))
    
    # Omitted fields will be set to default values.
    print(Person(name="Fred"))
    
    # A & prefix yields a pointer to the struct in Go, but in Python, we just use the instance.
    print(Person(name="Ann", age=40))
    
    # It’s idiomatic to encapsulate new class instance creation in functions.
    print(new_person("Jon"))
    
    # Access class fields with a dot.
    s = Person(name="Sean", age=50)
    print(s.name)
    
    # You can also use dots with class instances.
    sp = s
    print(sp.age)
    
    # Class instances are mutable.
    sp.age = 51
    print(sp.age)
    
    # If a class is only used for a single value, we don’t have to give it a name.
    # Use an anonymous class type here.
    Dog = type('Dog', (object,), {'name': '', 'isGood': False})
    dog = Dog()
    dog.name = "Rex"
    dog.isGood = True
    print(dog)

if __name__ == "__main__":
    main()