---
source: https://iinventedlight.com/library/notes/python-generators-yield.md
title: "Yield expressions and generator functions"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "PSF License Version 2 (Python docs); prose restates cited source lines in own words"
license_family: python-psf
attribution: "Summary by iinventedlight (AI-assisted). Sources: Python Software Foundation, 6. Expressions, PSF License Version 2; Python Software Foundation, 9. Classes, PSF License Version 2."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-06
status: published
checked_on: 2026-11-06
as_of: 2026-11-06
confidence: medium
untested: "No Python interpreter was run for this note; only the fetched documentation pages were read."
category: coding-references
topic_area: "code-python: generators"
tags: [python, generators, yield]
client: Librarian
sources:
  - id: S1
    title: "6. Expressions"
    publisher: Python Software Foundation
    url: https://docs.python.org/3/reference/expressions.html
    accessed: 2026-11-06
    license: "PSF License Version 2"
  - id: S2
    title: "9. Classes"
    publisher: Python Software Foundation
    url: https://docs.python.org/3/tutorial/classes.html
    accessed: 2026-11-06
    license: "PSF License Version 2"
---
# Yield expressions and generator functions

A yield expression is used when defining a generator function. [S1]

## Yield

yield expression is used when defining a generator function. [S1]

## Classes vs generators

Classes provide a means of bundling data and functionality together. [S2]

Each class instance can have attributes attached to it for maintaining its state. [S2]

## Claims

- id: C1
  claim: yield defines generator functions.
  source: S1
  evidence: "yield expression is used when defining a generator function"

- id: C2
  claim: Classes bundle data and functionality.
  source: S2
  evidence: "Classes provide a means of bundling data and functionality together."

- id: C3
  claim: Instances hold state attributes.
  source: S2
  evidence: "Each class instance can have attributes attached to it for maintaining its state."

- id: C4
  claim: Creating a class creates a new type.
  source: S2
  evidence: "Creating a new class creates a new type of object"

## Sources

- [S1] 6. Expressions. Python Software Foundation. https://docs.python.org/3/reference/expressions.html . License: PSF License Version 2. Accessed 2026-11-06.

- [S2] 9. Classes. Python Software Foundation. https://docs.python.org/3/tutorial/classes.html . License: PSF License Version 2. Accessed 2026-11-06.


License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted). Source: Python Software Foundation (Python 3 docs). PSF License Version 2 (https://docs.python.org/3/license.html).