Is there a way in Go to list all the standard/built-in packages (i.e., the packages which come installed with a GoLang installation)?
I have a list of packages and I want to figure out which packages are standard.
Is there a way in Go to list all the standard/built-in packages (i.e., the packages which come installed with a GoLang installation)?
I have a list of packages and I want to figure out which packages are standard.
You can use the new golang.org/x/tools/go/packages
for this. This provides a programmatic interface for most of go list
:
package main
import (
"fmt"
"golang.org/x/tools/go/packages"
)
func main() {
pkgs, err := packages.Load(nil, "std")
if err != nil {
panic(err)
}
fmt.Println(pkgs)
// Output: [archive/tar archive/zip bufio bytes compress/bzip2 ... ]
}
To get a isStandardPackage()
you can store it in a map, like so:
package main
import (
"fmt"
"golang.org/x/tools/go/packages"
)
var standardPackages = make(map[string]struct{})
func init() {
pkgs, err := packages.Load(nil, "std")
if err != nil {
panic(err)
}
for _, p := range pkgs {
standardPackages[p.PkgPath] = struct{}{}
}
}
func isStandardPackage(pkg string) bool {
_, ok := standardPackages[pkg]
return ok
}
func main() {
fmt.Println(isStandardPackage("fmt")) // true
fmt.Println(isStandardPackage("nope")) // false
}
Use the go list std
command to list the standard packages. The special import path std
expands to all packages in the standard Go library (doc).
Exec that command to get the list in a Go program:
cmd := exec.Command("go", "list", "std")
p, err := cmd.Output()
if err != nil {
// handle error
}
stdPkgs = strings.Fields(string(p))
If you want a simple solution, you could check if a package is present in $GOROOT/pkg. All standard packages are installed here.