New function for searching and importing plugin

operator-plugin.go

@@ -4,10 +4,6 @@
 // operator-plugin.go
 package expr
 
-import (
-	"io"
-)
-
 //-------- plugin term
 
 func newPluginTerm(tk *Token) (inst *term) {
@@ -22,31 +18,13 @@ func newPluginTerm(tk *Token) (inst *term) {
 
 func evalPlugin(ctx ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
-	var moduleSpec any
+	var count int
 
 	if childValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	dirList := buildSearchDirList("plugin", ENV_EXPR_PLUGIN_PATH)
+	if count, err = importPluginFromSearchPath(childValue); err == nil {
-	count := 0
-	it := NewAnyIterator(childValue)
-	for moduleSpec, err = it.Next(); err == nil; moduleSpec, err = it.Next() {
-		if module, ok := moduleSpec.(string); ok {
-			if err = importPlugin(dirList, module); err != nil {
-				break
-			}
-			count++
-		} else {
-			err = opTerm.Errorf("expected string as item nr %d, got %s", it.Index()+1, TypeName(moduleSpec))
-			break
-		}
-	}
-	if err == io.EOF {
-		err = nil
-	}
-
-	if err == nil {
 		v = int64(count)
 	}
 	return

plugins.go

@@ -6,6 +6,7 @@ package expr
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"plugin"
 	"strings"
@@ -90,6 +91,29 @@ func importPlugin( /*ctx ExprContext,*/ dirList []string, name string) (err erro
 	return
 }
 
+func importPluginFromSearchPath(name any) (count int, err error) {
+	var moduleSpec any
+
+	dirList := buildSearchDirList("plugin", ENV_EXPR_PLUGIN_PATH)
+	count = 0
+	it := NewAnyIterator(name)
+	for moduleSpec, err = it.Next(); err == nil; moduleSpec, err = it.Next() {
+		if module, ok := moduleSpec.(string); ok {
+			if err = importPlugin(dirList, module); err != nil {
+				break
+			}
+			count++
+		} else {
+			err = fmt.Errorf("expected string as item nr %d, got %s", it.Index()+1, TypeName(moduleSpec))
+			break
+		}
+	}
+	if err == io.EOF {
+		err = nil
+	}
+	return
+}
+
 func loadModules(dirList []string, moduleNames []string) (err error) {
 	for _, name := range moduleNames {
 		if err1 := importPlugin(dirList, name); err1 != nil {

t_plugin_test.go

@@ -8,9 +8,16 @@ import (
 	"testing"
 )
 
-func _TestImportPlugin(t *testing.T) {
+func TestImportPlugin(t *testing.T) {
-	if err := importPlugin([]string{"test-resources"}, "json"); err != nil {
+	t.Setenv("PLUGINS", "${HOME}/go/src/git.portale-stac.it/go")
-		t.Errorf("importPlugin() failed: %v", err)
+	t.Setenv("EXPR_PLUGIN_PATH","${PLUGINS}/expr-json-plugin:${PLUGINS}/expr-csv-plugin")
+
+	gotCount, gotErr := importPluginFromSearchPath("json")
+	if gotCount != 1 {
+		t.Errorf("Import count: got=%d, want=1", gotCount)
+	}
+	if gotErr != nil {
+		t.Errorf("importPlugin() failed: %v", gotErr)
 	}
 }