How to List Public Methods of a Go Package?

Listing Public Methods of a Package in Go

Question:

How is it possible to enumerate the public methods of a package in Go? Consider the following code structure:

main.go:

package main

func main() {
    // list public methods in here
}

libs/method.go:

package libs

func Result1() {
    fmt.Println("method Result1")
}

func Result2() {
    fmt.Println("method Result2")
}

Answer:

Regrettably, Go lacks a direct feature for this request. When a package is imported, the compiler may remove unused methods during optimization. Thus, the mere importing of a package does not guarantee the presence of all methods.

Alternatives:

Static Analysis:

You can parse the package's source code and extract function declarations using Go's reflection library. Consider the following example:

import (
    "fmt"
    "go/parser"
    "go/token"
)

func main() {
    fileset := token.NewFileSet()
    packages, err := parser.ParseDir(fileset, "./libs", nil, 0)
    if err != nil {
        fmt.Println("Parsing failed:", err)
        return
    }

    methods := []string{}
    for _, p := range packages {
        // Get all methods in each source file.
        for _, f := range p.Files {
            for _, dec := range f.Decls {
                if fn, ok := dec.(*parser.FuncDecl); ok && fn.Name.IsExported() {
                    methods = append(methods, fn.Name.String())
                }
            }
        }
    }

    fmt.Println("Exported methods in package 'libs':", methods)
}

Note: This approach only provides function declarations, not their implementations.

Dynamic Reflection:

Alternatively, you could use Go's reflect package at runtime to inspect the methods of a value. However, this requires having an initialized instance of the type in question.

Remember that these approaches have limitations and may not be suitable for all use cases.

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