Question

When you open a file for the purpose of retrieving a pickled object from it, what file access mode do you use?

Short answer

Answer: The correct file access mode is 'rb', which combines reading and binary modes.

Step-by-step solution

Understand Pickling

Pickling is the process of serializing data into a binary format, while unpickling is the deserialization of the binary data back into the original format. In Python, the `pickle` module is used for pickling and unpickling data.

List the Different File Access Modes in Python

Python provides several file access modes for reading, writing or appending to a file: 1. `'r'`: Read mode (default) - Opens a file for reading. 2. `'w'`: Write mode - Opens a file for writing, overwrites the file if it exists, or creates a new file if it doesn't. 3. `'a'`: Append mode - Opens a file for writing, appends to the file if it exists, or creates a new file if it doesn't. 4. `'x'`: Exclusive creation - Create a new file, but raise an error if the file already exists. 5. `'b'`: Binary mode - Opens a file in binary format. 6. `'t'`: Text mode (default) - Opens a file in text format. File access modes can be combined (e.g., `'rb'` for reading a binary file).

Choose the Correct File Access Mode for Retrieving a Pickled Object

When retrieving a pickled object from a file, you want to read the binary data from the file. As stated before, the `'r'` mode is for reading and the `'b'` mode is for binary access. Therefore, the correct file access mode is `'rb'`, which combines reading and binary modes.