Loading a plugin
- Go course
- Advanced
- Lesson 21/68
- 4 min
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.
Practice 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.
Starter code
package main
import (
"fmt"
"plugin"
)
func main() {
// buraya yaz
}Sample 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)
}Expected output
true
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does <code>Lookup</code> return?
- A plugin.Symbol and an error Correct answer
- Only a function
- A file path
- A goroutine
Explanation: Lookup returns a plugin.Symbol (really an any) and an error; you type-assert it to the real type before use.
2 Ask for the symbol
sym, err := p.____("Selam")sym, err := p.Lookup("Selam")Explanation: Lookup finds an exported symbol by name.
3 Loading steps
| Term | Meaning |
|---|---|
1. plugin.Open |
Load the file |
2. Lookup |
Find the symbol |
3. Type assertion |
Convert to the real type |
4. Call |
Use the function |