Loading a plugin

Learn to load a plugin with plugin.Open.

Loading a plugin

plugin.Open loads the file; opening the same file again returns the same *plugin.Plugin. Then you ask for a symbol by name with Lookup:

p, err := plugin.Open("selam.so")
if err != nil { log.Fatal(err) }
sym, err := p.Lookup("Selam")
if err != nil { log.Fatal(err) }

Error checking is required at both steps.

Opening the same plugin again

A plugin is loaded only once per process; its init functions also run once. Changing the file and reopening it doesn't bring in the new code. If hot reloading is needed you must build with a different file name or use a separate process.

Exercise Open and look up

Write loadSymbol(path, name string) error: return the error from plugin.Open(path), then the error from p.Lookup(name). In main, print the result of loadSymbol("x.so", "Selam") != nil.

Show example solution

package main

import (
    "fmt"
    "plugin"
)

func loadSymbol(path, name string) error {
    p, err := plugin.Open(path)
    if err != nil {
        return err
    }
    _, err = p.Lookup(name)
    return err
}

func main() {
    fmt.Println(loadSymbol("x.so", "Selam") != nil)
}

Test yourself

What does <code>Lookup</code> return?
- A plugin.Symbol and an error
- Only a function
- A file path
- A goroutine
Show answer

A plugin.Symbol and an error — Lookup returns a plugin.Symbol (really an any) and an error; you type-assert it to the real type before use.

Ask for the symbol

sym, err := p.____("Selam")

Show answer

sym, err := p.Lookup("Selam")

Loading steps

1. plugin.Open

Load the file
2. Lookup

Find the symbol
3. Type assertion

Convert to the real type
4. Call

Use the function

Next lesson: Plugin symbol

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies