Dekorator python mendapatkan nama fungsi

Dekorator bisa menjadi topik yang menakutkan saat pertama kali ditemui. Sementara The Zen of Python menyatakan "Harus ada satu– dan sebaiknya hanya satu cara yang jelas untuk melakukannya", ada banyak cara yang sama validnya untuk mengimplementasikan dekorator yang sama. Metode yang berbeda ini dapat dikategorikan sebagai berbasis fungsi, berbasis kelas, atau campuran keduanya. Dalam posting ini saya akan menjelaskan desain dan perilaku dekorator Python dan memberikan contoh dekorator yang sering saya gunakan dalam kode saya sendiri

Apa itu Dekorator?

Dalam Python, semuanya benar-benar objek, termasuk fungsi. Karena fungsi adalah objek, mereka dapat diteruskan sebagai argumen ke fungsi lain, mereka dapat menjadi nilai balik dari suatu fungsi, dan mereka dapat ditugaskan ke variabel. Jika Anda memahami konsep-konsep ini maka Anda memiliki semua yang Anda butuhkan untuk memahami dekorator

Dekorator adalah objek yang dapat dipanggil yang mengambil fungsi sebagai parameter input. Saya secara khusus mengatakan "objek yang dapat dipanggil" daripada "fungsi" karena Python memungkinkan Anda membuat jenis objek yang dapat dipanggil lainnya. Fitur bahasa yang menarik inilah yang memungkinkan kita membuat dekorator berbasis kelas, seperti yang akan kita lihat sebentar lagi

Dekorator Sederhana

Dekorator adalah pembungkus yang memungkinkan Anda mengeksekusi kode sebelum dan sesudah fungsi "dibungkus" (atau "dihiasi") dijalankan. Dengan membuat fungsi dekorator secara manual, efek "pembungkus" ini dapat dengan mudah didemonstrasikan. Pertimbangkan modul

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

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"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

• Baris 2.

  >>> decorated_function()
  Preparing to execute: undecorated_function
  I FORBID you from modifying how this function behaves!
  Finished executing: undecorated_function

  7 menerima fungsi sebagai parameter, membuatnya menjadi dekorator

• Baris 3.

  >>> decorated_function()
  Preparing to execute: undecorated_function
  I FORBID you from modifying how this function behaves!
  Finished executing: undecorated_function

  8 (didefinisikan dalam

  >>> decorated_function()
  Preparing to execute: undecorated_function
  I FORBID you from modifying how this function behaves!
  Finished executing: undecorated_function

  7) memungkinkan kita untuk mengeksekusi kode sebelum dan sesudah menjalankan fungsi yang dibungkus

• Baris 5. Pernyataan cetak ini akan dijalankan sebelum fungsi yang dibungkus.

• Baris 6. Fungsi yang dibungkus dijalankan dalam

  >>> decorated_function()
  Preparing to execute: undecorated_function
  I FORBID you from modifying how this function behaves!
  Finished executing: undecorated_function

  8

• Baris 7. Pernyataan cetak ini akan dijalankan setelah fungsi yang dibungkus

• Baris 9. Ini mungkin bagian yang paling membingungkan.

  >>> decorated_function()
  Preparing to execute: undecorated_function
  I FORBID you from modifying how this function behaves!
  Finished executing: undecorated_function

  8 adalah nilai kembalian dari fungsi dekorator (

  >>> decorated_function()
  Preparing to execute: undecorated_function
  I FORBID you from modifying how this function behaves!
  Finished executing: undecorated_function

  7). Pada titik ini, fungsi yang dibungkus (

  >>> undecorated_function = simple_decorator(undecorated_function)
  >>> undecorated_function()
  Preparing to execute: undecorated_function
  I FORBID you from modifying how this function behaves!
  Finished executing: undecorated_function

  _3) BELUM telah dieksekusi.

• Baris 12. Kami akan menggunakan fungsi ini untuk menunjukkan cara kerja

  >>> decorated_function()
  Preparing to execute: undecorated_function
  I FORBID you from modifying how this function behaves!
  Finished executing: undecorated_function

  7

Buka shell Python interaktif dan jalankan

>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

Harap perhatikan perbedaan antara memanggil fungsi (

>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

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>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Terakhir, kami mengeksekusi

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>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Ini adalah hasil yang kami harapkan setelah menerapkan

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Inilah yang terjadi ketika Anda mendekorasi fungsi menggunakan sintaks

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>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

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"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@simple_decorator
def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Mari kita verifikasi bahwa perilaku fungsi telah dimodifikasi

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Seperti yang Anda lihat,

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@simple_decorator
def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@simple_decorator
def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Jenis dekorator ini bagus, tetapi bagaimana jika fungsi asli kita memiliki satu atau lebih parameter masukan? . Apa yang dapat kita lakukan untuk memperbaikinya?

Meneruskan Argumen ke Fungsi Terbungkus

Memperbaiki ini sangat mudah. Ingat, saat kita menjalankan fungsi "dibungkus", kita benar-benar menjalankan fungsi yang dikembalikan oleh fungsi dekorator (

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Namun, kami perlu mengakomodasi semua kemungkinan kombinasi parameter masukan. Kita dapat melakukan ini dengan memodifikasi

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@simple_decorator
def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

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"""decorators.better"""
def a_better_decorator(function_to_decorate):
    def function_wrapper(*args, **kwargs):

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate(*args, **kwargs)
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@a_better_decorator
def greeting_anonymous():
    print("Hello anonymous website viewer!")


@a_better_decorator
def greeting_personal(name="Aaron"):
    print(f"Hello {name}!")

Mari kita uji versi ini dengan dua fungsi yang dihias,

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@simple_decorator
def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@simple_decorator
def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Ini berfungsi persis seperti yang kita butuhkan, nilai yang kita berikan ke

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@simple_decorator
def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@simple_decorator
def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Meneruskan Argumen ke Dekorator

Dekorator yang telah kita buat sejauh ini tentu saja berguna untuk berbagai skenario, tetapi mereka juga terbatas karena tidak ada cara untuk menyampaikan argumen kepada dekorator itu sendiri. Apa bedanya dengan dekorator terakhir yang kita buat?

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Jika Anda ingat kembali ke awal posting ini, saya menyebutkan bahwa, secara umum, ada dua cara berbeda untuk mengimplementasikan dekorator Python. berbasis fungsi dan berbasis kelas. Contoh yang telah kita lihat sejauh ini semuanya berbasis fungsi. Kecuali jika Anda perlu membuat dekorator yang menerima argumen, Anda harus menggunakan desain berbasis fungsi ini karena lebih mudah dibaca dan membutuhkan lebih sedikit sarang/lekukan daripada desain berbasis kelas yang setara.

Namun, saat Anda perlu meneruskan argumen ke dekorator, tidak ada keuntungan menggunakan desain berbasis fungsi atau berbasis kelas. Mari kita lihat desain berbasis fungsi terlebih dahulu karena ini merupakan perkembangan alami dari dekorator yang telah kita periksa

Desain Berbasis Fungsi

Bentuk generik dekorator berbasis fungsi yang menerima argumen diberikan di bawah ini

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Untuk meneruskan argumen ke dekorator, kami menambahkan fungsi pembungkus lain, yang disebut

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

>>> undecorated_function = simple_decorator(undecorated_function)
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Untuk memahami cara kerjanya, Anda perlu menyadari bahwa Baris 15 (tempat kita menerapkan dekorator ke suatu fungsi) sebenarnya adalah .

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

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Bandingkan ini dengan dekorator lain yang telah kita buat. ketika suatu fungsi didekorasi dengan

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@simple_decorator
def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

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Mari jalankan REPL dan uji dekorator ini. Kami juga akan memverifikasi bahwa kami masih dapat menggunakan fungsi yang didekorasi seperti yang diharapkan dengan meneruskan argumen yang mengubah perilakunya

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Seperti yang Anda lihat, argumen yang diteruskan ke dekorator (

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Fungsi, Kelas, dan Callable

Apakah Anda akrab dengan? .

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"""decorators.better"""
def a_better_decorator(function_to_decorate):
    def function_wrapper(*args, **kwargs):

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate(*args, **kwargs)
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@a_better_decorator
def greeting_anonymous():
    print("Hello anonymous website viewer!")


@a_better_decorator
def greeting_personal(name="Aaron"):
    print(f"Hello {name}!")

"""decorators.better"""
def a_better_decorator(function_to_decorate):
    def function_wrapper(*args, **kwargs):

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate(*args, **kwargs)
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@a_better_decorator
def greeting_anonymous():
    print("Hello anonymous website viewer!")


@a_better_decorator
def greeting_personal(name="Aaron"):
    print(f"Hello {name}!")

Sintaks panggilan,

"""decorators.better"""
def a_better_decorator(function_to_decorate):
    def function_wrapper(*args, **kwargs):

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate(*args, **kwargs)
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@a_better_decorator
def greeting_anonymous():
    print("Hello anonymous website viewer!")


@a_better_decorator
def greeting_personal(name="Aaron"):
    print(f"Hello {name}!")

"""decorators.better"""
def a_better_decorator(function_to_decorate):
    def function_wrapper(*args, **kwargs):

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate(*args, **kwargs)
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@a_better_decorator
def greeting_anonymous():
    print("Hello anonymous website viewer!")


@a_better_decorator
def greeting_personal(name="Aaron"):
    print(f"Hello {name}!")

Desain Berbasis Kelas

Dekorator yang sama dapat diimplementasikan menggunakan instance kelas yang dapat dipanggil

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"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Perbedaan utama antara desain berbasis fungsi dan berbasis kelas adalah bagaimana argumen yang diteruskan ke dekorator ditangani. Dalam pendekatan berbasis fungsi, argumen tersedia untuk

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

"""decorators.better"""
def a_better_decorator(function_to_decorate):
    def function_wrapper(*args, **kwargs):

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate(*args, **kwargs)
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


@a_better_decorator
def greeting_anonymous():
    print("Hello anonymous website viewer!")


@a_better_decorator
def greeting_personal(name="Aaron"):
    print(f"Hello {name}!")

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Kami dapat memastikan bahwa dekorator ini berperilaku persis sama dengan versi berbasis fungsi

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Desain Mana yang Lebih Baik?

Apakah ada keuntungan menggunakan salah satu desain dekorator? . Namun, saya mengakui bahwa desain berbasis fungsi lebih konvensional karena gagasan objek yang dapat dipanggil yang merupakan turunan dari kelas (bukan fungsi) bukanlah yang diharapkan kebanyakan orang ketika mereka menemukan konsep dekorator.

Selain itu, tidak ada manfaat yang jelas untuk memilih satu desain dari yang lain. Anda harus menggunakan desain yang paling masuk akal bagi Anda

Selalu Gunakan >>> decorated_function() Preparing to execute: undecorated_function I FORBID you from modifying how this function behaves! Finished executing: undecorated_function5

Saya sengaja meninggalkan sesuatu yang sangat penting dari contoh dekorator ini. Anda harus SELALU menghias

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Saat kami memeriksa nama dan tanda tangan fungsi

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>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

Sekarang, jika kita memeriksa

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(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

Mengapa saya tidak menyertakan dekorator

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Mudah-mudahan Anda memiliki pemahaman yang lebih baik tentang bagaimana dekorator dirancang dan bagaimana perilakunya di Python. Sisa dari posting ini akan berisi contoh dekorator yang sering saya gunakan dalam proyek Python saya bersama dengan fungsi pytest yang menunjukkan penggunaan yang dimaksud

Contoh. Batas Waktu Fungsi

Jika Anda pernah menulis kode yang berinteraksi dengan layanan luar, Anda mungkin pernah mengalami situasi di mana program Anda terhenti menunggu respons tanpa ada cara untuk membatalkan pemanggilan fungsi. Salah satu cara untuk melepaskan diri adalah dengan dekorator

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

Sintaks yang digunakan pada Baris 6 di atas mencegah pengguna menentukan argumen posisional dengan dekorator

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Sangat mudah digunakan. Cukup hiasi fungsi apa saja dengan

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Dalam skenario pengujian sederhana di bawah ini, fungsi

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

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(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

Contoh. Coba Ulang Fungsi

Contoh berikutnya mirip dengan dekorator

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Untuk menggunakannya, Anda menentukan satu set

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Definisi dekorator sebenarnya dimulai pada Baris 26 di bawah. Sebelum itu, Pengecualian khusus

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

Kita dapat menggunakan dekorator

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Dengan kode di bawah ini, kami akan mencoba memanggil

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Akhirnya, fungsi

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

(venv) decorators $ python
Python 3.7.6 (default, Jan 19 2020, 06:08:58)
[Clang 11.0.0 (clang-1100.0.33.8)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from decorators.basic import * 
>>> undecorated_function()
I FORBID you from modifying how this function behaves!
>>> decorated_function = simple_decorator(undecorated_function)

Contoh. Log Tanda Tangan Panggilan dan Waktu Eksekusi

Aplikasi dekorator yang paling umum mungkin adalah logging. Sangat mudah untuk mengetahui alasannya, memiliki kemampuan untuk menjalankan kode segera sebelum dan setelah suatu fungsi dipanggil memungkinkan Anda untuk melaporkan informasi dan menangkap metrik

Dekorator ini menggunakan desain berbasis kelas, dan memungkinkan pengguna menyediakan logger khusus. Jika tidak ada yang tersedia, logger akan dibuat berdasarkan modul yang berisi fungsi yang dibungkus

Setiap kali fungsi dipanggil, dekorator

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

• Stempel waktu saat fungsi dipanggil
• nama fungsi dan nilai semua argumen yang diberikan ke fungsi (mis. e. tanda panggilan)
• Waktu berlalu saat menjalankan fungsi

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Kode di bawah menguji dekorator

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Fitur yang bagus dari dekorator ini adalah tanda tangan panggilan fungsi berisi nama dan nilai dari semua argumen kata kunci, bahkan jika nilai default digunakan atau jika nama tidak diberikan saat panggilan terjadi. Misalnya, panggilan ke fungsi yang dihias pada Baris 28 adalah

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

Demikian pula, panggilan ke fungsi yang dihias di Baris 36 adalah

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Jika kita menjalankan

"""decorators.basic"""
def simple_decorator(function_to_decorate):
    def function_wrapper():

        print(f"Preparing to execute: {function_to_decorate.__name__}")
        function_to_decorate()
        print(f"Finished executing: {function_to_decorate.__name__}")

    return function_wrapper


def undecorated_function():
    print("I FORBID you from modifying how this function behaves!")

>>> decorated_function()
Preparing to execute: undecorated_function
I FORBID you from modifying how this function behaves!
Finished executing: undecorated_function

Ringkasan

Jika Anda ingin mengunduh semua atau sebagian kode dari pos ini, Anda dapat dengan mudah melakukannya dari intisari Github yang ditautkan di bawah ini

Dekorator Python

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