Docstrings

Docstrings are string literals used to document modules, classes, methods, and functions. They are written as part of the source code and are intended to describe what the object does, its parameters, return values, and any side effects.

In Python, a docstring is defined as the first statement in the object’s body. It is assigned to the object's __doc__ attribute and is accessible at runtime via the help() function or by reading __doc__ directly.

Docstrings typically follow conventions such as PEP 257 and can be formatted in various styles (reStructuredText, Google style, NumPy style). The choice of format affects readability and tooling, not runtime behavior.

Example:

def add(a, b):

"""Return the sum of a and b.

Parameters:

a: first addend

b: second addend

Returns:

The sum of a and b

"""

return a + b

Other languages use documentation comments rather than docstrings. For example, Java uses JavaDoc, and C# uses XML documentation comments. These serve similar purposes but differ in syntax and tooling.

Docstrings support automated documentation generation (Sphinx, pydoc) and runtime introspection. They help developers understand code without reading implementation details and assist when building external APIs or libraries.

Best practices include providing a concise summary, detailing parameters and return values, and avoiding duplication with code. Keep docstrings up to date as code evolves.