How to Use the Command 'cargo doc' (with Examples)

The cargo doc command is a versatile tool within the Rust programming language ecosystem. It is used to automatically generate documentation for Rust projects and their dependencies. This command helps developers create organized, structured, and easily navigable documentation for their projects, facilitating better understanding and collaboration across teams. By using cargo doc, developers can ensure that their code is not only functional but also well-documented, promoting transparency and ease of use.

Use Case 1: Build the Documentation for the Current Project and All Dependencies

Code:

cargo doc

Motivation: When working on a Rust project, you may often find yourself needing to understand how both your code and its dependencies work together. Generating documentation for the entire project, including all its dependencies, is crucial when reviewing or sharing your work. This complete documentation set can be particularly beneficial when onboarding new team members or engaging with the open-source community, as it offers a full view of the project’s ecosystem.

Explanation:

• cargo doc: This command will generate HTML documentation from Rust source files. By default, it builds the documentation for the entire crate and any dependencies it may have. This ensures that users can easily browse through the functions and modules available in both the project’s code and any libraries it relies on.

Example Output: After running cargo doc, the generated documentation files are typically stored in the target/doc directory. Open the index.html file within this directory to start exploring the documentation in your web browser.

Use Case 2: Do Not Build Documentation for Dependencies

Code:

cargo doc --no-deps

Motivation: In certain situations, you might only be interested in the documentation for your codebase and not the external libraries it depends on. This can occur when you are confident in your understanding of the dependencies or when those libraries are too extensive. By focusing just on your project, you can cut down on build times and disk space used.

Explanation:

• cargo doc: This generates HTML documentation for your project.
• --no-deps: This flag prevents the command from generating documentation for the project’s dependencies. It restricts the output to only the project-specific modules, functions, and structs, allowing you to concentrate purely on your contributions to the code.

Example Output: The documentation will be limited to the project’s code, available in the target/doc directory. It won’t include any third-party libraries or dependencies, thus making the documentation generation process quicker and more focused.

Use Case 3: Build and Open the Documentation in a Browser

Code:

cargo doc --open

Motivation: After generating documentation, it’s often necessary to quickly access it to check how well the documentation reads, or to verify its completeness. Manually navigating to the documentation files and opening them in a browser can be a hassle. Automating this process ensures an immediate review, making it an efficient step in the development workflow.

Explanation:

• cargo doc: This generates the documentation for your project and dependencies.
• --open: After generating the documentation, this flag will automatically open the default web browser to display the documentation’s starting point, usually index.html.

Example Output: Upon successful completion, your default web browser will launch, displaying the main page of your project’s documentation. This eliminates any delay or need to manually navigate to documentation files.

Use Case 4: Build and View the Documentation of a Particular Package

Code:

cargo doc --open --package package

Motivation: In complex projects where multiple packages (or crates) are involved, there might be times when your focus is narrowed to a specific package. Whether you are part of a large team working on various aspects of a project, or a solo developer managing a multi-package project, concentrating on the documentation for a single package aids in reducing cognitive load and speeding up the debugging or feature development processes.

Explanation:

• cargo doc: Responsible for generating documentation.
• --open: Automatically opens the generated documentation in the browser.
• --package package: Specifies a particular package within a workspace or multi-crate project for which documentation should be generated and opened. This isolates the documentation produced, keeping your focus solely on the specified package.

Example Output: The documentation for the specified package is generated and opened in your web browser, allowing you to view only what’s relevant to that package without distraction from other project modules.

Conclusion:

The cargo doc command is an indispensable tool for Rust developers seeking to keep their projects well-documented. Each use case described above highlights a scenario where cargo doc can be used effectively, whether it’s through generating comprehensive project documentation or focusing on specific components. By leveraging these examples, developers can ensure they maintain high-quality documentation standards, fostering better code comprehension and community engagement.