Modules and Packages Flashcards

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

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

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

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

Answer: __init__.py

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.

What is a 'namespace package' in Python 3?

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

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

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

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

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

What is the purpose of `sys.path`?

Answer: It is a list of directories Python searches when importing modules

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

Which statement correctly imports only the `sqrt` function from the `math` module?

Answer: from math import sqrt

`from math import sqrt` binds the name `sqrt` directly in the current namespace without importing the full module.

What value does `__name__` hold when a module is imported (not run directly)?

Answer: The module's fully qualified name

When a module is imported, `__name__` is set to the module's fully qualified name (e.g., `'mypackage.mymodule'`), not `'__main__'`.