Refactor to use core.ObjectReader and core.ObjectWriter

* New function signatures provide the necessary interface to stream data from disk when using filesystem-based storage in the future
* New function signatures provide proper error handling
* ObjectReader and ObjectWriter interfaces added to avoid future refactoring, currently are type aliases for io.ReadCloser and io.WriteCloser respectively
* Object.Reader now returns (ObjectReader, error)
* Object.Writer now returns (ObjectWriter, error)
* File.Contents now returns (string, error)
* File.Lines now returns ([]string, error)
* Blob.Reader now returns (core.ObjectReader, error)
* Added internal close helper function for deferred calls to Close that need to check the return value

1 files changed, 17 insertions, 2 deletions

diff --git a/core/object.go b/core/object.go
index 74ea555..d56a44a 100644
--- a/core/object.go
+++ b/core/object.go
@@ -10,6 +10,21 @@ var (
 	ObjectNotFoundErr = errors.New("object not found")
 )
 
+// TODO: Consider adding a Hash function to the ObjectReader and ObjectWriter
+//       interfaces that returns the hash calculated for the reader or writer.
+
+// ObjectReader is a generic representation of an object reader.
+//
+// ObjectReader implements io.ReadCloser. Close should be called when finished
+// with it.
+type ObjectReader io.ReadCloser
+
+// ObjectWriter is a generic representation of an object writer.
+//
+// ObjectWriter implements io.WriterCloser. Close should be called when finished
+// with it.
+type ObjectWriter io.WriteCloser
+
 // Object is a generic representation of any git object
 type Object interface {
 	Hash() Hash
@@ -17,8 +32,8 @@ type Object interface {
 	SetType(ObjectType)
 	Size() int64
 	SetSize(int64)
-	Reader() io.Reader
-	Writer() io.Writer
+	Reader() (ObjectReader, error)
+	Writer() (ObjectWriter, error)
 }
 
 // ObjectStorage generic storage of objects