Better error handling

goldsmith.go

@@ -75,22 +75,14 @@ func (gs *goldsmith) makeStage() stage {
 	return s
 }
 
-func (gs *goldsmith) NewFile(relPath string) File {
-	return &file{relPath: relPath}
-}
-
-func (gs *goldsmith) SetError(err error) {
-	gs.err = err
-}
-
-func (gs *goldsmith) taskSingle(ts TaskerSingle) {
+func (gs *goldsmith) chainSingle(ts ChainerSingle) {
 	s := gs.makeStage()
 
 	var wg sync.WaitGroup
 	for file := range s.input {
 		wg.Add(1)
 		go func(f File) {
-			s.output <- ts.TaskSingle(gs, f)
+			s.output <- ts.ChainSingle(gs, f)
 			wg.Done()
 		}(file)
 	}
@@ -101,18 +93,26 @@ func (gs *goldsmith) taskSingle(ts TaskerSingle) {
 	}()
 }
 
-func (gs *goldsmith) taskMultiple(tm TaskerMultiple) {
+func (gs *goldsmith) chainMultiple(tm ChainerMultiple) {
 	s := gs.makeStage()
-	tm.TaskMultiple(gs, s.input, s.output)
+	tm.ChainMultiple(gs, s.input, s.output)
 }
 
-func (gs *goldsmith) Task(task interface{}) Goldsmith {
-	if gs.err == nil {
-		switch t := task.(type) {
-		case TaskerSingle:
-			gs.taskSingle(t)
-		case TaskerMultiple:
-			gs.taskMultiple(t)
+func (gs *goldsmith) NewFile(relPath string) File {
+	return &file{relPath: relPath}
+}
+
+func (gs *goldsmith) Chain(chain interface{}, err error) Goldsmith {
+	if gs.err != nil {
+		return gs
+	}
+
+	if gs.err = err; gs.err != nil {
+		switch t := chain.(type) {
+		case ChainerSingle:
+			gs.chainSingle(t)
+		case ChainerMultiple:
+			gs.chainMultiple(t)
 		}
 	}
 
@@ -124,13 +124,13 @@ func (gs *goldsmith) Complete(dstDir string) ([]File, error) {
 
 	var files []File
 	for file := range s.output {
+		if file.Error() == nil {
 			data := file.Data()
 			if data == nil {
 				continue
 			}
 
 			absPath := filepath.Join(dstDir, file.Path())
-
 			if err := os.MkdirAll(path.Dir(absPath), 0755); err != nil {
 				file.SetError(err)
 				continue
@@ -147,6 +147,7 @@ func (gs *goldsmith) Complete(dstDir string) ([]File, error) {
 				file.SetError(err)
 				continue
 			}
+		}
 
 		files = append(files, file)
 	}

types.go

@@ -23,21 +23,20 @@
 package goldsmith
 
 type Goldsmith interface {
-	Task(task interface{}) Goldsmith
+	Chain(task interface{}, err error) Goldsmith
 	Complete(dstDir string) ([]File, error)
 }
 
-type TaskerSingle interface {
-	TaskSingle(ctx Context, file File) File
+type ChainerSingle interface {
+	ChainSingle(ctx Context, file File) File
 }
 
-type TaskerMultiple interface {
-	TaskMultiple(ctx Context, input, output chan File)
+type ChainerMultiple interface {
+	ChainMultiple(ctx Context, input, output chan File)
 }
 
 type Context interface {
 	NewFile(srcDir string) File
-	SetError(err error)
 }
 
 type File interface {