Mastering Go Packages: How to Discover Exported Functionalities

To find out which exported functionalities (e.g., functions, constants, variables, types) a Go package provides, you can use the following methods:

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1. Official Documentation

• Use the Go official package documentation.
• For any package (e.g., math), navigate to its page (e.g., math package) to see a list of exported items.
• Exported items are listed with descriptions and usage examples.

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2. go doc Command

• Run the go doc command to see the documentation of a package directly in your terminal.

• Example:
  

   go doc math
  

  Output:
  

   package math // import "math"
  
   Constants:
       Pi = 3.141592653589793 // The mathematical constant π.
   Functions:
       Abs(x float64) float64
       ...
  

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3. IDE or Code Editor Features

• Modern IDEs like GoLand, VS Code, or LiteIDE provide code navigation tools.
• When you import a package in your Go file, you can use features like IntelliSense or Auto-Completion to see all exported functionalities.
  • Example: After importing math, type math. to see suggestions for all exported members.

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4. Source Code

• Go to the source code of the package to check for exported items. Look for names starting with capital letters.

• For example, you can find the math package source at its repository:
  

   https://github.com/golang/go/tree/master/src/math
  

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5. godoc Command

• If you have the godoc tool installed locally, you can view documentation in your browser.
• Install in ubuntu: sudo apt install golang-golang-x-tools

• Start a local documentation server:
  

   godoc -http=:6060
  

• Open http://localhost:6060 in your browser and navigate to the package.

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Example with the math Package

Exported Functionalities

You can find:

• Constants: Pi, E, etc.
• Functions: Abs, Sin, Cos, etc.

How to Check (Terminal Example):

go doc math.Pi

Output:

package math // import "math"

const Pi = 3.141592653589793
    Pi is the ratio of a circle's circumference to its diameter.