revamp the Headers API

1. Move common methods of AccountHeaders, ContainerHeaders,
   ObjectHeaders into a base type Headers.

2. Fold Headers into RequestOptions to remove one of the two optional
   arguments on request methods. The new Headers.ToOpts() method
   offers a nice experience for users passing Headers to request
   methods.

   The Update() methods keep the explicit Headers argument since the
   Headers argument is not optional there.

   The only downside is that we lose a bit of type-safety because
   RequestOptions takes any Headers instance, so e.g. ContainerHeaders
   could be passed to Object.Upload(). I believe the benefits outweigh
   this problem.

1 files changed, 24 insertions, 31 deletions

diff --git a/object.go b/object.go
index 4af37e6..fb72aeb 100644
--- a/object.go
+++ b/object.go
@@ -104,7 +104,7 @@ func (o *Object) Headers() (ObjectHeaders, error) {
 		return ObjectHeaders{}, err
 	}
 
-	headers := ObjectHeaders(headersFromHTTP(resp.Header))
+	headers := ObjectHeaders{headersFromHTTP(resp.Header)}
 	err = headers.Validate()
 	if err != nil {
 		return headers, err
@@ -124,8 +124,7 @@ func (o *Object) Update(headers ObjectHeaders, opts *RequestOptions) error {
 		Method:            "POST",
 		ContainerName:     o.c.name,
 		ObjectName:        o.name,
-		Headers:           headersToHTTP(headers),
-		Options:           opts,
+		Options:           cloneRequestOptions(opts, headers.Headers),
 		ExpectStatusCodes: []int{202},
 	}.Do(o.c.a.backend)
 	if err == nil {
@@ -134,18 +133,17 @@ func (o *Object) Update(headers ObjectHeaders, opts *RequestOptions) error {
 	return err
 }
 
-//Upload creates the object using a PUT request. To add URL parameters, pass
-//a non-nil *RequestOptions.
+//Upload creates the object using a PUT request.
 //
 //If you do not have an io.Reader, but you have a []byte or string instance
 //containing the object, wrap it in a *bytes.Reader instance like so:
 //
 //	var buffer []byte
-//	o.Upload(bytes.NewReader(buffer), headers, opts)
+//	o.Upload(bytes.NewReader(buffer), opts)
 //
 //	//or...
 //	var buffer string
-//	o.Upload(bytes.NewReader([]byte(buffer)), headers, opts)
+//	o.Upload(bytes.NewReader([]byte(buffer)), opts)
 //
 //If you have neither an io.Reader nor a []byte or string, but you have a
 //function that generates the object's content into an io.Writer, use
@@ -166,16 +164,15 @@ func (o *Object) Update(headers ObjectHeaders, opts *RequestOptions) error {
 //This function can be used regardless of whether the object exists or not.
 //
 //A successful PUT request implies Invalidate() since it may change metadata.
-func (o *Object) Upload(content io.Reader, headers ObjectHeaders, opts *RequestOptions) error {
-	if headers == nil {
-		headers = make(ObjectHeaders)
-	}
-	tryComputeContentLength(content, headers)
-	tryComputeEtag(content, headers)
+func (o *Object) Upload(content io.Reader, opts *RequestOptions) error {
+	opts = cloneRequestOptions(opts, nil)
+	hdr := ObjectHeaders{opts.Headers}
+	tryComputeContentLength(content, hdr)
+	tryComputeEtag(content, hdr)
 
 	//could not compute Etag in advance -> need to check on the fly
 	var hasher hash.Hash
-	if !headers.Etag().Exists() {
+	if !hdr.Etag().Exists() {
 		hasher = md5.New()
 		if content != nil {
 			content = io.TeeReader(content, hasher)
@@ -186,7 +183,6 @@ func (o *Object) Upload(content io.Reader, headers ObjectHeaders, opts *RequestO
 		Method:            "PUT",
 		ContainerName:     o.c.name,
 		ObjectName:        o.name,
-		Headers:           headersToHTTP(headers),
 		Options:           opts,
 		Body:              content,
 		ExpectStatusCodes: []int{201},
@@ -253,7 +249,7 @@ func tryComputeEtag(content io.Reader, headers ObjectHeaders) {
 //	}
 //
 //	obj := container.Object("greeting-for-susan-and-jeffrey")
-//	err := obj.UploadWithWriter(nil, nil, func(w io.Writer) error {
+//	err := obj.UploadWithWriter(nil, func(w io.Writer) error {
 //	    err := greeting(w, "Susan")
 //	    if err == nil {
 //	        err = greeting(w, "Jeffrey")
@@ -262,11 +258,11 @@ func tryComputeEtag(content io.Reader, headers ObjectHeaders) {
 //	})
 //
 //If you do not need an io.Writer, always use Upload instead.
-func (o *Object) UploadWithWriter(headers ObjectHeaders, opts *RequestOptions, callback func(io.Writer) error) error {
+func (o *Object) UploadWithWriter(opts *RequestOptions, callback func(io.Writer) error) error {
 	reader, writer := io.Pipe()
 	errChan := make(chan error)
 	go func() {
-		err := o.Upload(reader, headers, opts)
+		err := o.Upload(reader, opts)
 		reader.CloseWithError(err) //stop the writer if it is still writing
 		errChan <- err
 	}()
@@ -280,12 +276,11 @@ func (o *Object) UploadWithWriter(headers ObjectHeaders, opts *RequestOptions, c
 //This operation fails with http.StatusNotFound if the object does not exist.
 //
 //A successful DELETE request implies Invalidate().
-func (o *Object) Delete(headers ObjectHeaders, opts *RequestOptions) error {
+func (o *Object) Delete(opts *RequestOptions) error {
 	_, err := Request{
 		Method:            "DELETE",
 		ContainerName:     o.c.name,
 		ObjectName:        o.name,
-		Headers:           headersToHTTP(headers),
 		Options:           opts,
 		ExpectStatusCodes: []int{204},
 	}.Do(o.c.a.backend)
@@ -313,18 +308,17 @@ func (o *Object) Invalidate() {
 //	str, err := object.Download(nil, nil).AsString()
 //
 //See struct DownloadedObject for details.
-func (o *Object) Download(headers ObjectHeaders, opts *RequestOptions) DownloadedObject {
+func (o *Object) Download(opts *RequestOptions) DownloadedObject {
 	resp, err := Request{
 		Method:            "GET",
 		ContainerName:     o.c.name,
 		ObjectName:        o.name,
-		Headers:           headersToHTTP(headers),
 		Options:           opts,
 		ExpectStatusCodes: []int{200},
 	}.Do(o.c.a.backend)
 	var body io.ReadCloser
 	if err == nil {
-		newHeaders := ObjectHeaders(headersFromHTTP(resp.Header))
+		newHeaders := ObjectHeaders{headersFromHTTP(resp.Header)}
 		err = newHeaders.Validate()
 		if err == nil {
 			o.headers = &newHeaders
@@ -347,18 +341,17 @@ func (o *Object) Download(headers ObjectHeaders, opts *RequestOptions) Downloade
 //
 //A successful COPY implies target.Invalidate() since it may change the
 //target's metadata.
-func (o *Object) CopyTo(target *Object, headers ObjectHeaders, opts *RequestOptions) error {
-	hdr := headersToHTTP(headers)
-	hdr.Set("Destination", target.FullName())
+func (o *Object) CopyTo(target *Object, opts *RequestOptions) error {
+	opts = cloneRequestOptions(opts, nil)
+	opts.Headers.Set("Destination", target.FullName())
 	if o.c.a.name != target.c.a.name {
-		hdr.Set("Destination-Account", target.c.a.name)
+		opts.Headers.Set("Destination-Account", target.c.a.name)
 	}
 
 	_, err := Request{
 		Method:            "COPY",
 		ContainerName:     o.c.name,
 		ObjectName:        o.name,
-		Headers:           hdr,
 		Options:           opts,
 		ExpectStatusCodes: []int{201},
 		DrainResponseBody: true,
@@ -373,10 +366,10 @@ func (o *Object) CopyTo(target *Object, headers ObjectHeaders, opts *RequestOpti
 //a DELETE request on the source object.
 //
 //A successful move implies Invalidate() on both the source and target side.
-func (o *Object) MoveTo(target *Object, headers ObjectHeaders, opts *RequestOptions) error {
-	err := o.CopyTo(target, headers, opts)
+func (o *Object) MoveTo(target *Object, copyOpts *RequestOptions, deleteOpts *RequestOptions) error {
+	err := o.CopyTo(target, copyOpts)
 	if err != nil {
 		return err
 	}
-	return o.Delete(nil, nil)
+	return o.Delete(deleteOpts)
 }