Manajer konteks open() baca-saja

Anda memiliki banyak berkas data untuk proyek deep learning berikutnya yang menghabiskan waktu berbulan-bulan untuk dikumpulkan dan dibersihkan. Akan sangat buruk jika tanpa sengaja Anda menimpa salah satu berkas tersebut saat mencoba membacanya untuk pelatihan, sehingga Anda memutuskan untuk membuat versi baca-saja dari manajer konteks open() untuk digunakan dalam proyek Anda.

Manajer konteks open() biasa:

menerima nama berkas dan mode ('r' untuk membaca, 'w' untuk menulis, atau 'a' untuk menambahkan/append)
membuka berkas untuk membaca, menulis, atau menambahkan
menyerahkan kontrol kembali ke konteks beserta referensi ke berkas tersebut
menunggu hingga konteks selesai
lalu menutup berkas sebelum keluar

Manajer konteks Anda akan melakukan hal yang sama, kecuali ia hanya akan menerima nama berkas sebagai argumen dan hanya akan membuka berkas untuk membaca.

Latihan ini adalah bagian dari kursus

Menulis Function di Python

Petunjuk latihan

Serahkan kontrol dari open_read_only() ke blok konteks, memastikan bahwa objek read_only_file ditetapkan ke my_file.
Gunakan metode .close() milik read_only_file untuk memastikan Anda tidak membiarkan berkas tetap terbuka.

Latihan interaktif praktis

Cobalah latihan ini dengan menyelesaikan kode contoh berikut.

@contextlib.contextmanager
def open_read_only(filename):
  """Open a file in read-only mode.

  Args:
    filename (str): The location of the file to read

  Yields:
    file object
  """
  read_only_file = open(filename, mode='r')
  # Yield read_only_file so it can be assigned to my_file
  ____ ____
  # Close read_only_file
  ____.____()

with open_read_only('my_file.txt') as my_file:
  print(my_file.read())

Edit dan Jalankan Kode

Latihan ini adalah bagian dari kursus

Menulis Function di Python

SkillTag.level.intermediateSkillTag.label

4.8+

Mulai Kursus Gratis

The goal of this course is to transform you into a Python expert, and so the first chapter starts off with best practices when writing functions. You'll cover docstrings and why they matter and how to know when you need to turn a chunk of code into a function. You will also learn the details of how Python passes arguments to functions, as well as some common gotchas that can cause debugging headaches when calling functions.

Exercise 1: Docstrings Exercise 2: Crafting a docstring Exercise 3: Retrieving docstrings Exercise 4: Docstrings to the rescue!Exercise 5: DRY and "Do One Thing"Exercise 6: Extract a function Exercise 7: Split up a function Exercise 8: Pass by assignment Exercise 9: Mutable or immutable?Exercise 10: Best practice for default arguments

If you've ever seen the "with" keyword in Python and wondered what its deal was, then this is the chapter for you! Context managers are a convenient way to provide connections in Python and guarantee that those connections get cleaned up when you are done using them. This chapter will show you how to use context managers, as well as how to write your own.

Exercise 1: Menggunakan context manager Exercise 2: Jumlah kucing Exercise 3: Kecepatan kucing Exercise 4: Menulis context manager Exercise 5: Context manager timer()Exercise 6: Manajer konteks open() baca-saja

Latihan Saat Ini

Exercise 7: Topik lanjutan Exercise 8: Kapan menggunakan context manager Exercise 9: Mengambil data dari NASDAQ Exercise 10: Mengubah direktori kerja

Decorators are an extremely powerful concept in Python. They allow you to modify the behavior of a function without changing the code of the function itself. This chapter will lay the foundational concepts needed to thoroughly understand decorators (functions as objects, scope, and closures), and give you a good introduction into how decorators are used and defined. This deep dive into Python internals will set you up to be a superstar Pythonista.

Exercise 1: Functions are objects Exercise 2: Building a command line data app Exercise 3: Reviewing your co-worker's code Exercise 4: Returning functions for a math game Exercise 5: Scope Exercise 6: Understanding scope Exercise 7: Modifying variables outside local scope Exercise 8: Closures Exercise 9: Checking for closure Exercise 10: Closures keep your values safe Exercise 11: Decorators Exercise 12: Using decorator syntax Exercise 13: Defining a decorator

Now that you understand how decorators work under the hood, this chapter gives you a bunch of real-world examples of when and how you would write decorators in your own code. You will also learn advanced decorator concepts like how to preserve the metadata of your decorated functions and how to write decorators that take arguments.

Exercise 1: Real-world examples Exercise 2: Print the return type Exercise 3: Counter Exercise 4: Decorators and metadata Exercise 5: Preserving docstrings when decorating functions Exercise 6: Measuring decorator overhead Exercise 7: Decorators that take arguments Exercise 8: Run_n_times()Exercise 9: HTML Generator Exercise 10: Timeout(): a real world example Exercise 11: Tag your functions Exercise 12: Check the return type Exercise 13: Great job!