How to use the command 'godoc' (with examples)
The ‘godoc’ command is a tool that allows users to generate and view documentation for Go packages. It provides a convenient way to access detailed documentation for the packages and functions within the Go programming language.
Use case 1: Display help for package “fmt”
Code:
godoc fmt
Motivation: When working with Go packages, it is often helpful to have access to documentation that explains the functionality, usage, and examples of each package. By using godoc fmt, users can quickly access the documentation for the ‘fmt’ package, which is a commonly used package in Go for formatting input and output.
Explanation: The command godoc fmt is used to display the documentation for the ‘fmt’ package. The argument ‘fmt’ represents the name of the package for which the documentation is requested.
Example output: The output of the command will display the detailed documentation for the ‘fmt’ package, including the list of available functions, their parameters, and examples of usage.
Use case 2: Display help for the function “Printf” of “fmt” package
Code:
godoc fmt Printf
Motivation: When working with specific functions within a package, it is useful to have access to dedicated documentation for those functions. By using godoc fmt Printf, users can obtain detailed help for the ‘Printf’ function within the ‘fmt’ package, which is used for formatted printing in Go.
Explanation: The command godoc fmt Printf is used to display the documentation for the ‘Printf’ function within the ‘fmt’ package. The argument ‘fmt’ represents the package name, and ‘Printf’ represents the specific function within that package.
Example output: The output of the command will display the detailed documentation for the ‘Printf’ function, including its signature, parameters, and examples of how to use it.
Use case 3: Serve documentation as a web server on port 6060
Code:
godoc -http=:6060
Motivation: Sometimes it is more convenient to access the Go package documentation through a web browser rather than the command line. By using godoc -http=:6060, users can start a local web server that provides a web-based interface for browsing Go package documentation.
Explanation: The command godoc -http=:6060 starts the ‘godoc’ tool as a web server on port 6060. This allows users to access the documentation through a web browser by visiting http://localhost:6060 in their preferred browser.
Example output: The web server will start and display a list of all available Go packages. Users can then navigate through the documentation by clicking on the desired package, function, or type.
Use case 4: Create an index file
Code:
godoc -write_index -index_files=path/to/file
Motivation: In some cases, users may want to save the package index information to a file for later use. By using godoc -write_index -index_files=path/to/file, users can create an index file that contains the package information for all imported packages.
Explanation: The command godoc -write_index -index_files=path/to/file generates an index file that contains the package information for all imported packages. The argument -write_index instructs ‘godoc’ to write the index file, and -index_files=path/to/file specifies the location and name of the index file.
Example output: The index file will be created at the specified location and will contain the information about all imported Go packages, which can be used later for offline browsing or programmatic access.
Use case 5: Use the given index file to search the docs
Code:
godoc -http=:6060 -index -index_files=path/to/file
Motivation: When working with a large number of Go packages, searching through the documentation can become time-consuming. By using godoc -http=:6060 -index -index_files=path/to/file, users can utilize a pre-generated index file to enable search functionality within the web server.
Explanation: The command godoc -http=:6060 -index -index_files=path/to/file starts the ‘godoc’ tool as a web server on port 6060, utilizing the specified index file for improved searching capabilities. The -index argument enables searching, and -index_files=path/to/file specifies the location and name of the index file.
Example output: The web server will start with enhanced search functionality, allowing users to search for specific packages, functions, or types within the Go documentation. Search results will be displayed in the web browser, making it easier to find the required information.
Conclusion:
The ‘godoc’ command is a powerful tool for generating and viewing documentation for Go packages. By utilizing the various use cases outlined above, Go developers can access detailed help and insights into their code, making it easier to understand and maintain. Whether using it through the command line or as a web server, ‘godoc’ provides essential functionality for any Go developer.
