Kepriye cara kelas lan obyek gumana ing Python?

Question

Accepted Answer

A **class** minangka blueprint kanggo nggawe **objects** (instances) sing nggabung data (attributes) lan perilaku (methods). OOP Python nduweni fleksibilitas lan sawetara konvensi khas, utamane `self` sing eksplisit.

## Nggawe kelas

```python
class Dog:
    species = "Canis familiaris"     # CLASS attribute (shared by all instances)

def __init__(self, name, age):   # the constructor — runs on creation
        self.name = name              # INSTANCE attributes (per object)
        self.age = age

def bark(self):                   # a method — `self` is the instance
        return f"{self.name} says woof"

d = Dog("Rex", 3)        # create an instance (calls __init__)
d.name                   # "Rex"
d.bark()                 # "Rex says woof"
```

## Self sing eksplisit

```python
def bark(self):          # `self` is ALWAYS the first parameter of a method
    return self.name      # access instance data through self
```

Beda karo akeh basa sing nduweni `this` sing implisit, Python mbutuhake **`self`** minangka parameter pisanan sing eksplisit saka saben method instance — iki nuduhake instance sing method dipanggil. Sampeyan ora perlu ngirim manual; `d.bark()` ngirim `d` minangka `self` kanthi otomatis.

## Attributes kelas lawan attributes instance

```python
Dog.species          # "Canis familiaris" — shared by all dogs
d.species            # also accessible from an instance
d.name               # "Rex" — unique to this instance
```

Attributes kelas dibagi ing kabeh instances; attributes instance (diatur via `self.x =`) minangka per-obyek.

## Tipe-tipe method

```python
class Circle:
    def area(self): ...                    # instance method — needs self

@classmethod
    def from_diameter(cls, d):             # class method — receives the CLASS (cls)
        return cls(d / 2)                   # often used as alternative constructors

@staticmethod
    def pi(): return 3.14159               # static — no self/cls, just namespaced
```

## Konvensi enkapsulasi

```python
self.public                # public
self._protected            # "internal use" by convention (not enforced)
self.__private             # name-mangled to _ClassName__private (stronger hiding)
```

Python ora duwe anggota pribadi sing sejati — underscores awal minangka konvensi sing nuduhake tujuan ("aja diraba iki"), ora pemberlakuan keras.

## Apa sing penting

Kelas minangka cara sampeyan model entitas lan atur kode ing Python berorientasi obyek — nggabung data lan perilaku sing kait-kelingan, digunakake akeh ing frameworks, domain modeling, lan aplikasi gedhe.

Ngerti konvensi Python khas — `self` sing eksplisit, constructor `__init__`, attributes kelas lawan instance, tiga tipe method (`instance`/`@classmethod`/`@staticmethod`), lan konvensi privasi underscores — iku penting kanggo nulis lan maca Python berorientasi obyek.

Iki beda banget karo basa liya (self eksplisit, privasi berbasis konvensi) mula ngerti kanthi apik ngakibatke kebingungan umum.