Python Modules and Packages 5

Question 1

What is an 'editable install' (`pip install -e .`)?

Accepted Answer

An install where the package source directory is linked so code changes take effect immediately without reinstalling

Answer

Editable installs (development mode) add the source directory to `sys.path` via a `.pth` file so changes to the source are reflected instantly.

Question 2

What is the purpose of `PYTHONPATH` environment variable?

Accepted Answer

It adds directories to `sys.path` at interpreter startup

Answer

Directories listed in `PYTHONPATH` (colon-separated on Unix) are prepended to `sys.path` when the interpreter starts.

Question 3

What does `importlib.import_module('os.path')` return?

Accepted Answer

The `os.path` module object

Answer

`importlib.import_module()` performs the import and returns the module object, equivalent to `import os.path; return os.path`.

Question 4

What is the effect of deleting a module from `sys.modules` and then reimporting it?

Accepted Answer

The module's source file is re-executed and a fresh module object is created

Answer

Removing a module from `sys.modules` causes the next import to treat it as never loaded, re-executing its code and producing a new module object.

Question 5

Which attribute on a package module object contains the list of paths used to find its submodules?

Accepted Answer

__path__

Answer

`__path__` is set on package modules to the list of directories searched for submodules; regular (non-package) modules do not have this attribute.

Python Practice Test