Python Modules and Packages 2

Question 1

What does the `__all__` variable in a module control?

Accepted Answer

Which names are exported when `from module import *` is used

Answer

`__all__` is a list of strings defining the public API exported by `from module import *`.

Question 2

Which file must exist in a directory for Python 2 to treat it as a package?

Accepted Answer

__init__.py

Answer

In Python 2, a directory must contain `__init__.py` to be recognized as a package; Python 3 introduced namespace packages that don't require it.

Question 3

What is a 'namespace package' in Python 3?

Accepted Answer

A package spread across multiple directories without an `__init__.py`

Answer

Namespace packages (PEP 420) allow a single logical package to span multiple directories with no `__init__.py` required.

Question 4

What does `importlib.reload(module)` do?

Accepted Answer

Re-executes the module's code in the existing module object

Answer

`importlib.reload()` re-runs the module source in the existing module namespace, so existing references to the old object still point to it.

Question 5

What is the purpose of `sys.path`?

Accepted Answer

It is a list of directories Python searches when importing modules

Answer

`sys.path` is the list of directories (and zip files) Python searches in order when resolving import statements.

Python Practice Test