Function ExampleAllowUndefinedVariables

expr_test.go:502–538

()

}

func ExampleAllowUndefinedVariables() {
	code := `name == nil ? "Hello, world!" : sprintf("Hello, %v!", name)`

	env := map[string]any{
		"sprintf": fmt.Sprintf,
	}

	options := []expr.Option{
		expr.Env(env),
		expr.AllowUndefinedVariables(), // Allow to use undefined variables.
	}

	program, err := expr.Compile(code, options...)
	if err != nil {
		fmt.Printf("%v", err)
		return
	}

	output, err := expr.Run(program, env)
	if err != nil {
		fmt.Printf("%v", err)
		return
	}
	fmt.Printf("%v\n", output)

	env["name"] = "you" // Define variables later on.

	output, err = expr.Run(program, env)
	if err != nil {
		fmt.Printf("%v", err)
		return
	}
	fmt.Printf("%v\n", output)

	// Output: Hello, world!
	// Hello, you!
}

func ExampleAllowUndefinedVariables_zero_value() {
	code := `name == "" ? foo + bar : foo + name`