Document and refactor vm package

native/db/db.go

@@ -27,7 +27,7 @@ type (
 )
 
 func init() {
-	vm.RegisterExternalClass("db", vm.ExternalClass("DB", "db.gb",
+	vm.RegisterExternalClass("db", vm.NewExternalClassLoader("DB", "db.gb",
 		// class methods
 		map[string]vm.Method{
 			"get_connection": getConnection,

native/plugin/plugin.go

@@ -42,7 +42,7 @@ var (
 )
 
 func init() {
-	vm.RegisterExternalClass("plugin", vm.ExternalClass("Plugin", "plugin.gb",
+	vm.RegisterExternalClass("plugin", vm.NewExternalClassLoader("Plugin", "plugin.gb",
 		// class methods
 		map[string]Method{
 			"new": newPlugin,

native/result/bindings.go

@@ -13,7 +13,7 @@ import (
 
 func init() {
 	vm.RegisterExternalClass(
-		"result", vm.ExternalClass(
+		"result", vm.NewExternalClassLoader(
 			"Result",
 			"result.gb",
 			map[string]vm.Method{

native/ripper/ripper.go

@@ -203,7 +203,7 @@ func tokenize(receiver Object, sourceLine int, t *Thread, args []Object) Object
 
 // Internal functions ===================================================
 func init() {
-	vm.RegisterExternalClass("ripper", vm.ExternalClass("Ripper", "ripper.gb",
+	vm.RegisterExternalClass("ripper", vm.NewExternalClassLoader("Ripper", "ripper.gb",
 		// class methods
 		map[string]vm.Method{
 			"instruction": instruction,

vm/class.go

@@ -38,9 +38,9 @@ var externalClasses = map[string][]ClassLoader{}
 var externalClassLock sync.Mutex
 
 // RegisterExternalClass will add the given class to the global registry of available classes
-func RegisterExternalClass(path string, c ...ClassLoader) {
+func RegisterExternalClass(name string, c ...ClassLoader) {
 	externalClassLock.Lock()
-	externalClasses[path] = c
+	externalClasses[name] = c
 	externalClassLock.Unlock()
 }
 
@@ -57,19 +57,19 @@ func buildMethods(m map[string]Method) []*BuiltinMethodObject {
 	return out
 }
 
-// ExternalClass helps define external go classes
-func ExternalClass(name, path string, classMethods, instanceMethods map[string]Method) ClassLoader {
+// NewExternalClassLoader helps define external go classes by generating a class loader function
+func NewExternalClassLoader(className, libPath string, classMethods, instanceMethods map[string]Method) ClassLoader {
 	return func(v *VM) error {
-		pg := v.initializeClass(name)
+		pg := v.initializeClass(className)
 		pg.setBuiltinMethods(buildMethods(classMethods), true)
 		pg.setBuiltinMethods(buildMethods(instanceMethods), false)
 		v.objectClass.setClassConstant(pg)
 
-		if path == "" {
+		if libPath == "" {
 			return nil
 		}
 
-		return v.mainThread.execGobyLib(path)
+		return v.mainThread.execGobyLib(libPath)
 	}
 }
 

vm/vm.go

@@ -63,11 +63,12 @@ type VM struct {
 	fileDir string
 	// args are command line arguments
 	args []string
-	// projectRoot is goby root's absolute path, which is $GOROOT/src/github.com/goby-lang/goby
-	projectRoot string
 
-	// libPath indicates the Goby (.gb) libraries path. Defaults to `<projectRoot>/lib`, unless
-	// DefaultLibPath is specified.
+	// Goby vm uses libPath to find standard libraries written in Goby
+	// the fallback order is:
+	// 1. $GOBY_ROOT/lib
+	// 2. /usr/local/Cellar/goby/VERSION/lib - installed via homebrew
+	// 3. $GOPATH/src/github.com/goby-lang/goby/lib - development environment
 	libPath string
 
 	channelObjectMap *objectMap
@@ -99,33 +100,10 @@ func New(fileDir string, args []string) (vm *VM, e error) {
 	}
 	vm.fileDir = fileDir
 
-	gobyRoot := os.Getenv("GOBY_ROOT")
-
-	if len(gobyRoot) == 0 {
-		vm.projectRoot = fmt.Sprintf("/usr/local/Cellar/goby/%s", Version)
-
-		_, err := os.Stat(vm.projectRoot)
-
-		if err != nil {
-			gp := os.Getenv("GOPATH")
-			path, _ := filepath.Abs(gp + "/src/github.com/goby-lang/goby")
-			_, err = os.Stat(path)
-
-			if err != nil {
-				e = fmt.Errorf("You haven't set $GOBY_ROOT properly")
-				return nil, e
-			}
-
-			vm.projectRoot = path
-		}
-	} else {
-		vm.projectRoot = gobyRoot
-	}
+	err := vm.assignLibPath()
 
-	if DefaultLibPath != "" {
-		vm.libPath = DefaultLibPath
-	} else {
-		vm.libPath = filepath.Join(vm.projectRoot, "lib")
+	if err != nil {
+		return nil, err
 	}
 
 	vm.initConstants()
@@ -150,6 +128,37 @@ func (vm *VM) newThread() (t Thread) {
 	return
 }
 
+// vm.assignLibPath looks up and assigns vm.libPath
+func (vm *VM) assignLibPath() (err error) {
+	if DefaultLibPath != "" {
+		vm.libPath = DefaultLibPath
+		return
+	}
+
+	gobyRoot := os.Getenv("GOBY_ROOT")
+
+	if len(gobyRoot) == 0 {
+		// if GOBY_ROOT is not set, fallback to homebrew's path
+		gobyRoot = fmt.Sprintf("/usr/local/Cellar/goby/%s", Version)
+
+
+		// if it's not installed via homebrew, assume it's in development env and Goby's source is under GOPATH
+		if _, err := os.Stat(gobyRoot); err != nil {
+			path, _ := filepath.Abs(os.Getenv("GOPATH") + "/src/github.com/goby-lang/goby")
+
+			if _, err = os.Stat(path); err != nil {
+				return fmt.Errorf("You haven't set $GOBY_ROOT properly")
+			}
+
+			gobyRoot = path
+		}
+	}
+
+	vm.libPath = filepath.Join(gobyRoot, "lib")
+
+	return
+}
+
 // ExecInstructions accepts a sequence of bytecodes and use vm to evaluate them.
 func (vm *VM) ExecInstructions(sets []*bytecode.InstructionSet, fn string) {
 	translator := newInstructionTranslator(fn)
@@ -172,8 +181,8 @@ func (vm *VM) ExecInstructions(sets []*bytecode.InstructionSet, fn string) {
 	cf.self = vm.mainObj
 	vm.mainThread.callFrameStack.push(cf)
 
-      // here is the final destination of Goby errors at the VM level, and we don't deal with them at this point.
-      // we only decide how the user program should react to them.
+	// here is the final destination of Goby errors at the VM level, and we don't deal with them at this point.
+	// we only decide how the user program should react to them.
 	// at vm level, we don't deal with the error itself
 	// we only decide how the program should react to it
 	defer func() {
@@ -183,8 +192,8 @@ func (vm *VM) ExecInstructions(sets []*bytecode.InstructionSet, fn string) {
 		case error:
 			panic(err)
 
-		// if the error is one of the Goby's errors, such as argument error, we need to handle it depending on the mode of execution.
-		// we need to handle it depends on the type of program execution
+			// if the error is one of the Goby's errors, such as argument error, we need to handle it depending on the mode of execution.
+			// we need to handle it depends on the type of program execution
 		case *Error:
 
 			// REPLMode: We handle the error inside the igb package, so don't need to do anything here
@@ -415,4 +424,4 @@ func (vm *VM) checkArgTypes(args []Object, sourceLine int, types ...string) *Err
 	}
 
 	return nil
-}
+}

vm/vm_test.go

@@ -257,7 +257,7 @@ func TestAutoIncrementLocalVariable(t *testing.T) {
 func TestLoadingGobyLibraryFail(t *testing.T) {
 	vm := initTestVM()
 
-	libFileFullPath := filepath.Join(vm.projectRoot, "lib/_library_not_existing.gb")
+	libFileFullPath := filepath.Join(vm.libPath, "_library_not_existing.gb")
 	expectedErrorMessage := fmt.Sprintf("open %s: no such file or directory", libFileFullPath)
 
 	err := vm.mainThread.execGobyLib("_library_not_existing.gb")