Question 1

Why do we use virtual environments (venv)?

Accepted Answer

To isolate each project's libraries from the system Python and from other projects, so versions do not conflict and installing does not need administrator privileges.

Question 2

What is the role of the pyproject.toml file?

Accepted Answer

It is the standard file that describes the build system [build-system], the project metadata [project] (name, version, dependencies, and required Python version), and tool settings under [tool.*].

Question 3

What is the difference between requirements and constraints files?

Accepted Answer

A requirements file states what must be installed, while a constraints file restricts the allowed versions of packages that may be installed, without adding any package by itself.

Question 4

What is the benefit of the src layout for organizing packages?

Accepted Answer

Putting the code inside a src folder prevents it from being imported accidentally from the current working directory, so tests are forced to use the installed package and packaging errors appear early.

Question 5

What does an editable install mean?

Accepted Answer

Installing the package so it points directly at the source files (pip install -e .), so your edits show up immediately without reinstalling.

Question 6

What is the difference between a wheel and a source distribution (sdist)?

Accepted Answer

A wheel is a built package ready to install by just copying files, while an sdist is a source archive that needs a build step on the user's machine and may need a compiler if it contains C extensions.

Question 7

How do you expose a CLI command from a Python package?

Accepted Answer

Define a console script in [project.scripts] inside pyproject.toml pointing to a main function, and installing creates an executable with that name in the environment's bin.

Question 8

How do you decide which Python versions your project supports?

Accepted Answer

Declare requires-python in pyproject.toml (such as >=3.11), then actually test on the minimum and the newest version in a CI matrix.

Question 9

How do you configure logging in a library or service without annoying its users?

Accepted Answer

In a library, create a logger named after the module with logging.getLogger(__name__) and no handlers or basicConfig, and leave configuration to the application, which decides the handlers, levels, and format.

Question 10

How do you separate configuration from secrets in a Python application?

Accepted Answer

Read configuration and secrets from environment variables or a secret manager at startup, convert them to a typed settings object that is validated once, and never put secrets in the code, the package, or Git.