Documentation Types — Reference Documentation Guide

In this tutorial, you will learn about Documentation Types. We cover key concepts, practical examples, and best practices to help you master this topic.

Reference documentation describes the system in precise detail. It covers API endpoints, function signatures, configuration options, and data schemas. Developers consult reference docs when they need an exact answer about how something works.

In this lesson, you will learn how to write accurate, complete, and usable reference documentation. You will understand automation strategies and how to keep reference docs synchronized with code.

What You'll Learn

You will understand the reference documentation type, write accurate API references, and automate reference doc generation from source code annotations.

Why It Matters

Reference documentation is the most frequently accessed documentation type. Inaccurate reference docs cause bugs, wasted time, and lost trust. Accurate reference docs are the foundation of a good developer experience.

Real-World Use

DodaTech generates DodaZIP API reference docs automatically from Python docstrings. This ensures the docs always match the code. The automation eliminated the category of support tickets caused by outdated parameter documentation.

flowchart LR
  A[Source Code] --> B[Docstrings]
  B --> C[Doc Generator]
  C --> D[Reference Docs]
  D --> E[Published Site]
  A:::current
  classDef current fill:#f90,color:#fff,stroke:#333,stroke-width:2px

Elements of Reference Documentation

Every reference entry should include the name and signature of the item being documented. Describe what it does in one sentence. List all parameters with types, defaults, and descriptions.

Document return values with types and descriptions. List all exceptions or errors the item can raise. Include one or more usage examples.

Keep entries consistent across the documentation set. Use the same structure for all functions, all endpoints, and all configuration options.

def compress_file(
    input_path: str,
    output_path: str | None = None,
    algorithm: str = "gzip",
    level: int = 6,
) -> CompressResult:
    """Compress a file using the specified algorithm.

    Args:
        input_path: Path to the file to compress.
        output_path: Optional output path. Defaults to input_path
            with the algorithm extension appended.
        algorithm: Compression algorithm. Supported: gzip, bzip2, xz.
        level: Compression level from 1 to 9. Higher values produce
            smaller output but take longer.

    Returns:
        CompressResult with input_size, output_size, ratio, time_ms.

    Raises:
        FileNotFoundError: If input_path does not exist.
        ValueError: If algorithm is not supported.
    """

Automation Strategies

Manual reference documentation quickly becomes outdated. Automate generation from source code annotations. Tools like Sphinx for Python, JSDoc for JavaScript, and rustdoc for Rust parse structured comments and generate HTML.

Maintain a CI step that regenerates reference docs and fails the build if they differ from the committed version. This ensures reference docs stay synchronized with code.

Reference docs should still be reviewed by a technical writer. Automation handles completeness and accuracy. The writer handles clarity, consistency, and organization.

# Generate reference documentation from Python docstrings
# This command parses all Python source files and generates HTML docs.

sphinx-apidoc src/dodazip -o docs/api
cd docs && make html

# Expected output:
# Generating API docs for dodazip...
# 3 modules documented
# Writing to docs/api/index.html

Common Mistakes

1. Incomplete Parameter Documentation

Missing parameter types or descriptions. Every parameter must be documented including defaults.

2. No Error Documentation

Only documenting the happy path. Users need to know what errors can occur and how to handle them.

3. Outdated Examples

Examples that use old parameter names or wrong return types. Examples must be updated when code changes.

4. Inconsistent Structure

Different styles for different functions confuse readers. Use a consistent template for all reference entries.

5. Too Much Explanation

Reference docs should describe what, not why. Save explanations for conceptual documentation.

6. Manual Updates

Manual reference doc updates inevitably fall behind code. Automate generation from source annotations.

7. No Cross-References

Reference entries that do not link to related functions, tutorials, or conceptual guides leave readers without context.

Practice Questions

1. What is the purpose of reference documentation?

To provide precise, complete details about APIs, functions, endpoints, and configuration options for users who need exact answers.

2. Why should reference documentation be automated?

Manual reference docs fall behind code changes. Automation ensures reference docs always match the current code.

3. What should every reference entry include?

Name, signature, description, all parameters with types and defaults, return value, exceptions, and usage examples.

4. How does reference documentation differ from conceptual documentation?

Reference documents what something does. Conceptual explains why it works that way.

5. Challenge: Take a function from an open-source project that lacks complete reference documentation. Write a complete reference entry including all parameters, return values, exceptions, and examples. Then verify the accuracy against the actual implementation.

FAQ

Mini Project

Choose a library or framework you use. Identify a module with incomplete reference documentation. Write complete reference entries for all public functions and classes following the structure in this lesson. Include all parameters, return types, exceptions, and usage examples. Verify accuracy against the implementation.

What's Next

Next: Project Documentation