Ok, now with shared base object

blob.go

@@ -8,31 +8,17 @@ package git
 import "C"
 import (
 	"unsafe"
-	"runtime"
 )
 
 type Blob struct {
-	ptr *C.git_blob
+	gitObject
 }
 
-func (o *Blob) Id() *Oid {
-	return newOidFromC(C.git_blob_id(o.ptr))
-}
-
-func (o *Blob) Type() ObjectType {
-	return OBJ_BLOB
-}
-
-func (o *Blob) Free() {
-	runtime.SetFinalizer(o, nil)
-	C.git_blob_free(o.ptr)
-}
-
-func (v *Blob) Size() int64 {
+func (v Blob) Size() int64 {
 	return int64(C.git_blob_rawsize(v.ptr))
 }
 
-func (v *Blob) Contents() []byte {
+func (v Blob) Contents() []byte {
 	size := C.int(C.git_blob_rawsize(v.ptr))
 	buffer := unsafe.Pointer(C.git_blob_rawcontent(v.ptr))
 	return C.GoBytes(buffer, size)

commit.go

@@ -9,34 +9,20 @@ extern int _go_git_treewalk(git_tree *tree, git_treewalk_mode mode, void *ptr);
 import "C"
 
 import (
-	"runtime"
 	"unsafe"
 	"time"
 )
 
 // Commit
 type Commit struct {
-	ptr *C.git_commit
+	gitObject
 }
 
-func (o *Commit) Id() *Oid {
-	return newOidFromC(C.git_commit_id(o.ptr))
-}
-
-func (o *Commit) Type() ObjectType {
-	return OBJ_COMMIT
-}
-
-func (o *Commit) Free() {
-	runtime.SetFinalizer(o, nil)
-	C.git_commit_free(o.ptr)
-}
-
-func (c *Commit) Message() string {
+func (c Commit) Message() string {
 	return C.GoString(C.git_commit_message(c.ptr))
 }
 
-func (c *Commit) Tree() (*Tree, error) {
+func (c Commit) Tree() (*Tree, error) {
 	var ptr *C.git_object
 
 	err := C.git_commit_tree(&ptr, c.ptr)
@@ -47,16 +33,16 @@ func (c *Commit) Tree() (*Tree, error) {
 	return allocObject(ptr).(*Tree), nil
 }
 
-func (c *Commit) TreeId() *Oid {
+func (c Commit) TreeId() *Oid {
 	return newOidFromC(C.git_commit_tree_id(c.ptr))
 }
 
-func (c *Commit) Author() *Signature {
+func (c Commit) Author() *Signature {
 	ptr := C.git_commit_author(c.ptr)
 	return newSignatureFromC(ptr)
 }
 
-func (c *Commit) Committer() *Signature {
+func (c Commit) Committer() *Signature {
 	ptr := C.git_commit_committer(c.ptr)
 	return newSignatureFromC(ptr)
 }

object.go

@@ -25,25 +25,41 @@ type Object interface {
 	Type() ObjectType
 }
 
+type gitObject struct {
+	ptr *C.git_object
+}
+
+func (o gitObject) Id() *Oid {
+	return newOidFromC(C.git_commit_id(o.ptr))
+}
+
+func (o gitObject) Type() ObjectType {
+	return ObjectType(C.git_object_type(o.ptr))
+}
+
+func (o gitObject) Free() {
+	runtime.SetFinalizer(o, nil)
+	C.git_commit_free(o.ptr)
+}
+
 func allocObject(cobj *C.git_object) Object {
-	var object Object
 
 	switch ObjectType(C.git_object_type(cobj)) {
 	case OBJ_COMMIT:
-		object = &Commit{cobj}
-		runtime.SetFinalizer(object, (*Commit).Free)
+		commit := &Commit{gitObject{cobj}}
+		runtime.SetFinalizer(commit, (*Commit).Free)
+		return commit
 
 	case OBJ_TREE:
-		object = &Tree{cobj}
-		runtime.SetFinalizer(object, (*Tree).Free)
+		tree := &Tree{gitObject{cobj}}
+		runtime.SetFinalizer(tree, (*Tree).Free)
+		return tree
 
 	case OBJ_BLOB:
-		object = &Blob{cobj}
-		runtime.SetFinalizer(object, (*Blob).Free)
-
-	default:
-		return nil
+		blob := &Blob{gitObject{cobj}}
+		runtime.SetFinalizer(blob, (*Blob).Free)
+		return blob
 	}
 
-	return object
+	return nil
 }

tree.go

@@ -14,20 +14,7 @@ import (
 )
 
 type Tree struct {
-	ptr *C.git_tree
-}
-
-func (o *Tree) Id() *Oid {
-	return newOidFromC(C.git_tree_id(o.ptr))
-}
-
-func (o *Tree) Type() ObjectType {
-	return OBJ_TREE
-}
-
-func (o *Tree) Free() {
-	runtime.SetFinalizer(o, nil)
-	C.git_tree_free(o.ptr)
+	gitObject
 }
 
 type TreeEntry struct {
@@ -44,7 +31,7 @@ func newTreeEntry(entry *C.git_tree_entry) *TreeEntry {
 	}
 }
 
-func (t *Tree) EntryByName(filename string) *TreeEntry {
+func (t Tree) EntryByName(filename string) *TreeEntry {
 	cname := C.CString(filename)
 	defer C.free(unsafe.Pointer(cname))
 
@@ -56,7 +43,7 @@ func (t *Tree) EntryByName(filename string) *TreeEntry {
 	return newTreeEntry(entry)
 }
 
-func (t *Tree) EntryByIndex(index uint64) *TreeEntry {
+func (t Tree) EntryByIndex(index uint64) *TreeEntry {
 	entry := C.git_tree_entry_byindex(t.ptr, C.size_t(index))
 	if entry == nil {
 		return nil
@@ -65,7 +52,7 @@ func (t *Tree) EntryByIndex(index uint64) *TreeEntry {
 	return newTreeEntry(entry)
 }
 
-func (t *Tree) EntryCount() uint64 {
+func (t Tree) EntryCount() uint64 {
 	num := C.git_tree_entrycount(t.ptr)
 	return uint64(num)
 }
@@ -81,7 +68,7 @@ func CallbackGitTreeWalk(_root unsafe.Pointer, _entry unsafe.Pointer, ptr unsafe
 	return C.int(callback(root, newTreeEntry(entry)))
 }
 
-func (t *Tree) Walk(callback TreeWalkCallback) error {
+func (t Tree) Walk(callback TreeWalkCallback) error {
 	err := C._go_git_treewalk(
 		t.ptr,
 		C.GIT_TREEWALK_PRE,