DEV Community: Bekzod

Python da decorator

Bekzod — Wed, 25 Jan 2023 04:36:37 +0000

Decorator larni tushunishdan avval Python da closure funksiyalar ko'rib chiqamiz.

def hello(name):
    # ichki funksiya
    def get_name():
        return f"Hello, {name}!"

    # ichki funksiyani qaytarish
    return get_name


hello_func = hello("Sarvar")
print(hello_func())  # Hello, Sarvar!

Closure bu ichma-ich funksiyada tashqi funksiya o'zgaruvchilarini ichki funksiyada foydalanish mumkin bo'ladi.
Quyida ikkita sonni ko'paytiradigan closure yaratamiz.

def multiplier(n):
    def mul(x):
        return x * n

    return mul


# Multiplier of 3
mul_three = multiplier(3)

# Multiplier of 5
mul_five = multiplier(5)

print(mul_three(9))  # 27
print(mul_five(3))  # 15
print(mul_five(mul_three(2)))  # 30

Decorator yaratishimiz da ham closure orqali amalga oshiramiz.
Decorator orqali boshqa funksiyada ishlatilgan holda uning xususiyatini o'zgartirishimiz mumkin bo'ladi.

Manba: Medium

Decorator funksiya argument sifatida funksiya qabul qiladi.

def make_decorator(func):
    def inner():
        # Ichki funksiya orqali func xususiyatlarini o'zgartirishimiz mumkin
        print("Dekorator ishlayapti")

        func()

    # Ichki funksiya qaytariladi
    return inner


def my_func():
    print("Dekorator uchun ishlatiladigan funksiya")


decorated_func = make_decorator(my_func)
decorated_func()

# Dekorator ishlayapti
# Dekorator uchun ishlatiladigan funksiya

Decorator funksiya @ orqali ishlatiladi.

@make_decorator
def my_func():
    print("Dekorator uchun ishlatiladigan funksiya")


my_func()

# Dekorator ishlayapti
# Dekorator uchun ishlatiladigan funksiya

Funksiyani argumentlar orqali decoratorda ishlatishni ko'rib chiqamiz.
2 ta sonni bo'ladigan divider(a, b) funksiya yaratamiz.

def divider(a, b):
    return a / b


print(divider(10, 5))  # 2.0
print(divider(10, 0))  # ZeroDivisionError: division by zero

b o'zgaruvchiga 0 qiymat beriladigan bo'lsa ZeroDevisionError xatolik qaytaradi, buni oldini olish uchun decorator funksiya yaratamiz.

def divide_decorator(func):
    def divide_inner(a, b):
        try:
            return func(a, b)
        except ZeroDivisionError:
            print("Nolga bo'lish mumkin emas!")

    return divide_inner


@divide_decorator
def divider(a, b):
    return a / b


print(divider(10, 5))  # 2.0
print(divider(10, 0))  # Nolga bo'lish mumkin emas!

Bitta funksiyada bir nechta decorator ishlatishimiz ham mumkin, bunda birinchisidan boshlab decoratorlar ishlab keladi.

def divide_decorator(func):
    def divide_inner(a, b):
        try:
            return func(a, b)
        except ZeroDivisionError:
            print("Nolga bo'lish mumkin emas!")

    return divide_inner


def increment_arg_if_second_zero(func):
    def inner(a, b):
        if b == 0:
            b += 1
        return func(a, b)

    return inner


@increment_arg_if_second_zero
@divide_decorator
def divider(a, b):
    return a / b


print(divider(10, 5))  # 2.0
print(divider(10, 0))  # 10.0

Keyingi qismlarda decorator lar bo'yicha murakkab funksiyalarni ko'rib chiqamiz.

Iterator va generator

Bekzod — Wed, 25 Jan 2023 03:36:14 +0000

Iterator

Python da iterator obyektlar __iter__ va __next__ metodlari orqali amalga oshiriladi. Iterator obyektni iterable tiplar list, tuple, dict, str va boshqa, iter() built_in metodi orqali yaratamiz va elementlarni olishda next() metodidan foydalanamiz.

Manba: Codingninjas

my_list = [2, 4, 8, 16, 32]

iterator = iter(my_list)

print(next(iterator))  # 2
print(next(iterator))  # 4
print(next(iterator))  # 8
print(next(iterator))  # 16
print(next(iterator))  # 32
print(next(iterator))  # StopIteration

Iterator oxirgi elementidan keyin next ishlatilsa StopIteration xatolik qaytaradi.

Xuddi shuni for loop orqali amalga oshiramiz.

my_list = [2, 4, 8, 16, 32]

for item in my_list:
    print(item)

# 2
# 4
# 8
# 16
# 32

Iterator obyekt elementlarini for loop orqali ham olishimiz mumkin.

my_list = [2, 4, 8, 16, 32]

iterator = iter(my_list)

for item in iterator:
    print(item)

# 2
# 4
# 8
# 16
# 32

__iter__ va __next__ metodlarni o'zgartirgan holda iterator obyekt yaratamiz.

class PowTwo:
    def __init__(self, limit=0):
        self.limit = limit

    def __iter__(self):
        self.n = 1
        return self

    def __next__(self):
        if self.n <= self.limit:
            pow_number = 2 ** self.n
            self.n += 1
            return pow_number
        else:
            raise StopIteration


numbers = PowTwo(5)
iterator = iter(numbers)

print(next(iterator))  # 2
print(next(iterator))  # 4
print(next(iterator))  # 8
print(next(iterator))  # 16
print(next(iterator))  # 32
print(next(iterator))  # StopIteration

iter() va next() built_in metodlar ishlatganimizda class da yozilgan __iter__ va __next__ metodlarga murojaat qilinadi.

numbers = PowTwo(5)
iterator = numbers.__iter__()

print(iterator.__next__())  # 2
print(iterator.__next__())  # 4
print(iterator.__next__())  # 8
print(iterator.__next__())  # 16
print(iterator.__next__())  # 32
print(iterator.__next__())  # StopIteration

Generator

Manba: Medium

Python da generator funksiya oddiy funksiyadek bo'ladi, faqat yield kalit so'zi orqali qiymat qaytariladi.

def generator():
    yield 1
    yield 2
    yield 3


for value in generator():
    print(value)
# 1
# 2
# 3

Generator funksiya generator obyekt qaytaradi.

print(generator())
# <generator object generator at 0x7f1af486aea0>

Generator obyekt dan iterator sifatida foydalanib next() orqali ham qiymatlarni olishimiz mumkin.

my_generator = generator()

print(next(my_generator))  # 1
print(next(my_generator))  # 2
print(next(my_generator))  # 3
print(next(my_generator))  # StopIteration

Nima uchun funksiyada `return` o'rniga `yield` ishlatilyapti?

return funksiyada berilgan qiymatni qaytaradi, yield esa ketma-ketlikni qaytarib yuboradi. Biz funksiyada butun bir ketma-ketlik xotirada saqlamasdan qaytarmoqchi bo'lsak yield foydalanishimiz kerak.

Raqamlar ro'yxatidan ularning kvadratlarini qaytaradigan generator funksiya yaratib ko'ramiz.

def square(nums):
    for num in nums:
        yield num ** 2


numbers = [1, 2, 3]
generator = square(numbers)

print(next(generator))  # 1
print(next(generator))  # 4
print(next(generator))  # 9
print(next(generator))  # StopIteration

Generator funksiya orqali qaytariladigan ketma-ketlikni sum() va boshqa iterable qabul qiladigan funksiyalar orqali ishlatsak ham bo'ladi.