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 'rb' (read-binary) file access mode should be used to retrieve a pickled object from a file in Python.

Step-by-step solution

Understand Pickling and File Access Modes

Pickling is a process in Python where the object hierarchy is converted into a byte stream. In other words, it is the process of converting a Python object into a bytestring. Conversely, unpickling is the process of converting a pickled byte stream back into the Python object hierarchy. When dealing with files, there are different access modes such as reading ('r'), writing ('w'), appending ('a'), and reading and writing ('r+'). To retrieve a pickled object, we need to open the file in the appropriate access mode to read the pickled content.

Choose the Correct File Access Mode

Since the task is to retrieve a pickled object from a file, we need to choose a file access mode that allows reading the file. The correct access mode for this purpose is 'rb'. 'rb' stands for "read-binary", which means the file is opened for reading in binary mode. The binary mode is used for pickled objects as they are stored as byte streams. In summary, one should use the 'rb' file access mode when opening a file to retrieve a pickled object from it.