go(BREAKING)!: use fmt.Errorf to wrap named errors, and use errors.Is to check

cmd/protoc-gen-go-tableau-loader/errors.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"path/filepath"
+
+	"google.golang.org/protobuf/compiler/protogen"
+)
+
+// generateError generates related error files.
+func generateError(gen *protogen.Plugin) {
+	filename := filepath.Join("errors." + pcExt + ".go")
+	g := gen.NewGeneratedFile(filename, "")
+	generateCommonHeader(gen, g)
+	g.P()
+	g.P("package ", *pkg)
+	g.P()
+	g.P(staticErrorContent)
+	g.P()
+}
+
+const staticErrorContent = `
+import (
+	"errors"
+)
+
+var ErrNotFound = errors.New("not found")`

cmd/protoc-gen-go-tableau-loader/main.go

@@ -37,7 +37,6 @@ func main() {
 		}
 		generateHub(gen)
 		generateError(gen)
-		generateCode(gen)
 		return nil
 	})
 }

cmd/protoc-gen-go-tableau-loader/messager.go

@@ -23,20 +23,16 @@ const (
 	pairPackage    = protogen.GoImportPath("github.com/tableauio/loader/pkg/pair")
 	timePackage    = protogen.GoImportPath("time")
 	sortPackage    = protogen.GoImportPath("sort")
+	fmtPackage     = protogen.GoImportPath("fmt")
 	protoPackage   = protogen.GoImportPath("google.golang.org/protobuf/proto")
 )
 
 // golbal container for record all proto filenames and messager names
 var messagers []string
-var errorsPackage protogen.GoImportPath
-var codePackage protogen.GoImportPath
 
 // generateMessager generates a protoconf file corresponding to the protobuf file.
 // Each wrapped struct type implement the Messager interface.
 func generateMessager(gen *protogen.Plugin, file *protogen.File) {
-	errorsPackage = protogen.GoImportPath(string(file.GoImportPath) + "/" + *pkg + "/" + errPkg)
-	codePackage = protogen.GoImportPath(string(file.GoImportPath) + "/" + *pkg + "/" + codePkg)
-
 	filename := filepath.Join(file.GeneratedFilenamePrefix + "." + pcExt + ".go")
 	g := gen.NewGeneratedFile(filename, "")
 	generateFileHeader(gen, file, g)
@@ -224,7 +220,7 @@ func genMapGetters(gen *protogen.Plugin, g *protogen.GeneratedFile, message *pro
 			g.P("d := ", container, ".Get", field.GoName, "()")
 			lastKeyName := keys[len(keys)-1].Name
 			g.P("if val, ok := d[", lastKeyName, "]; !ok {")
-			g.P(`return `, returnEmptyValue, `, `, errorsPackage.Ident("Errorf"), `(`, codePackage.Ident("NotFound"), `, "`, lastKeyName, `(%v) not found", `, lastKeyName, `)`)
+			g.P(`return `, returnEmptyValue, `, `, fmtPackage.Ident("Errorf"), `("`, lastKeyName, `(%v) %w", `, lastKeyName, `, ErrNotFound)`)
 			g.P("} else {")
 			g.P(`return val, nil`)
 			g.P("}")

cmd/protoc-gen-go-tableau-loader/ordered_map.go

@@ -179,7 +179,7 @@ func genOrderedMapGetters(gen *protogen.Plugin, g *protogen.GeneratedFile, md pr
 					keyName = fmt.Sprintf("BoolToInt(%s)", keyName)
 				}
 				g.P("if val, ok := conf.Get(", keyName, "); !ok {")
-				g.P(`return nil, `, errorsPackage.Ident("Errorf"), `(`, codePackage.Ident("NotFound"), `, "`, lastKeyName, `(%v) not found", `, lastKeyName, `)`)
+				g.P(`return nil, `, fmtPackage.Ident("Errorf"), `("`, lastKeyName, `(%v) %w", `, lastKeyName, `, ErrNotFound)`)
 				g.P("} else {")
 				g.P(`return val.First, nil`)
 				g.P("}")

test/go-tableau-loader/main.go

@@ -1,12 +1,12 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"time"
 
 	"github.com/tableauio/loader/test/go-tableau-loader/hub"
-	"github.com/tableauio/loader/test/go-tableau-loader/protoconf/loader/code"
-	"github.com/tableauio/loader/test/go-tableau-loader/protoconf/loader/xerrors"
+	"github.com/tableauio/loader/test/go-tableau-loader/protoconf/loader"
 	"github.com/tableauio/tableau/format"
 	"github.com/tableauio/tableau/load"
 	"github.com/tableauio/tableau/store"
@@ -33,7 +33,7 @@ func main() {
 
 	// error: not found
 	if _, err := conf.Get3(100001, 1, 999); err != nil {
-		if xerrors.Is(err, code.NotFound) {
+		if errors.Is(err, loader.ErrNotFound) {
 			fmt.Println("error: not found:", err)
 		}
 	}