feat(dispatch): Dispatch func can return 1-3 values, 2 being Cursor

Func implementations registered with Dispatch can return 1-3 values.
Only 1 value means it must be an error. 2 values means the first is
any output and the second is an error. 3 values means the first is any
output, the second is a Cursor, and the third is an error. Cursor will
be used for pagination of methods that support it.

api/fsi.go

@@ -63,7 +63,7 @@ func (h *FSIHandlers) statusHandler(routePrefix string) http.HandlerFunc {
 			return
 		}
 
-		res, err := h.inst.Dispatch(r.Context(), method, p)
+		res, _, err := h.inst.Dispatch(r.Context(), method, p)
 		if err != nil {
 			util.RespondWithError(w, err)
 			return
@@ -102,7 +102,7 @@ func (h *FSIHandlers) whatChangedHandler(routePrefix string) http.HandlerFunc {
 			return
 		}
 
-		res, err := h.inst.Dispatch(r.Context(), method, p)
+		res, _, err := h.inst.Dispatch(r.Context(), method, p)
 		if err != nil {
 			util.RespondWithError(w, err)
 			return
@@ -141,7 +141,7 @@ func (h *FSIHandlers) initHandler(routePrefix string) http.HandlerFunc {
 			return
 		}
 
-		res, err := h.inst.Dispatch(r.Context(), method, p)
+		res, _, err := h.inst.Dispatch(r.Context(), method, p)
 		if err != nil {
 			util.RespondWithError(w, err)
 			return
@@ -180,7 +180,7 @@ func (h *FSIHandlers) canInitDatasetWorkDirHandler(routePrefix string) http.Hand
 			return
 		}
 
-		res, err := h.inst.Dispatch(r.Context(), method, p)
+		res, _, err := h.inst.Dispatch(r.Context(), method, p)
 		if err != nil {
 			util.RespondWithError(w, err)
 			return
@@ -227,7 +227,7 @@ func (h *FSIHandlers) writeHandler(routePrefix string) http.HandlerFunc {
 			return
 		}
 
-		res, err := h.inst.Dispatch(r.Context(), method, p)
+		res, _, err := h.inst.Dispatch(r.Context(), method, p)
 		if err != nil {
 			util.RespondWithError(w, err)
 			return
@@ -274,7 +274,7 @@ func (h *FSIHandlers) createLinkHandler(routePrefix string) http.HandlerFunc {
 			return
 		}
 
-		res, err := h.inst.Dispatch(r.Context(), method, p)
+		res, _, err := h.inst.Dispatch(r.Context(), method, p)
 		if err != nil {
 			util.RespondWithError(w, err)
 			return
@@ -321,7 +321,7 @@ func (h *FSIHandlers) unlinkHandler(routePrefix string) http.HandlerFunc {
 			return
 		}
 
-		res, err := h.inst.Dispatch(r.Context(), method, p)
+		res, _, err := h.inst.Dispatch(r.Context(), method, p)
 		if err != nil {
 			util.RespondWithError(w, err)
 			return
@@ -368,7 +368,7 @@ func (h *FSIHandlers) checkoutHandler(routePrefix string) http.HandlerFunc {
 			return
 		}
 
-		res, err := h.inst.Dispatch(r.Context(), method, p)
+		res, _, err := h.inst.Dispatch(r.Context(), method, p)
 		if err != nil {
 			util.RespondWithError(w, err)
 			return
@@ -415,7 +415,7 @@ func (h *FSIHandlers) restoreHandler(routePrefix string) http.HandlerFunc {
 			return
 		}
 
-		res, err := h.inst.Dispatch(r.Context(), method, p)
+		res, _, err := h.inst.Dispatch(r.Context(), method, p)
 		if err != nil {
 			util.RespondWithError(w, err)
 			return

cmd/checkout.go

@@ -95,8 +95,7 @@ func (o *CheckoutOptions) Run() (err error) {
 		return err
 	}
 
-	_, err = inst.Filesys().Checkout(ctx, &lib.LinkParams{Dir: o.Dir, Refstr: ref})
-	if err != nil {
+	if err = inst.Filesys().Checkout(ctx, &lib.LinkParams{Dir: o.Dir, Refstr: ref}); err != nil {
 		return err
 	}
 	printSuccess(o.Out, "created and linked working directory %s for existing dataset", o.Dir)

cmd/restore.go

@@ -138,8 +138,7 @@ func (o *RestoreOptions) Run() (err error) {
 		Component: o.ComponentName,
 	}
 
-	_, err = inst.Filesys().Restore(ctx, &params)
-	if err != nil {
+	if err = inst.Filesys().Restore(ctx, &params); err != nil {
 		return err
 	}
 	if o.ComponentName != "" && o.Path == "" {

lib/access.go

@@ -51,7 +51,7 @@ func (p *CreateAuthTokenParams) Validate() error {
 // private key for the grantee.
 // Callers can provide either GranteeUsername OR GranteeProfileID
 func (m AccessMethods) CreateAuthToken(ctx context.Context, p *CreateAuthTokenParams) (string, error) {
-	res, err := m.d.Dispatch(ctx, dispatchMethodName(m, "createauthtoken"), p)
+	res, _, err := m.d.Dispatch(ctx, dispatchMethodName(m, "createauthtoken"), p)
 	if s, ok := res.(string); ok {
 		return s, err
 	}

lib/datasets.go

@@ -1311,8 +1311,7 @@ func (m *DatasetMethods) Pull(ctx context.Context, p *PullParams) (*dataset.Data
 			Refstr: ref.Human(),
 			Dir:    p.LinkDir,
 		}
-		fsiMethods := m.inst.Filesys()
-		if _, err = fsiMethods.Checkout(ctx, checkoutp); err != nil {
+		if err = m.inst.Filesys().Checkout(ctx, checkoutp); err != nil {
 			return nil, err
 		}
 	}

lib/datasets_test.go

@@ -593,7 +593,7 @@ func TestDatasetRequestsGetFSIPath(t *testing.T) {
 		Dir:    dsDir,
 		Refstr: "peer/movies",
 	}
-	if _, err := fsim.Checkout(ctx, p); err != nil {
+	if err := fsim.Checkout(ctx, p); err != nil {
 		t.Fatalf("error checking out dataset: %s", err)
 	}
 
@@ -874,7 +874,7 @@ func TestDatasetRequestsRemove(t *testing.T) {
 		Dir:    filepath.Join(datasetsDir, "cities"),
 		Refstr: "me/cities",
 	}
-	if _, err := fsim.Checkout(ctx, checkoutp); err != nil {
+	if err := fsim.Checkout(ctx, checkoutp); err != nil {
 		t.Fatal(err)
 	}
 
@@ -889,7 +889,7 @@ func TestDatasetRequestsRemove(t *testing.T) {
 		Dir:    filepath.Join(datasetsDir, "craigslist"),
 		Refstr: "me/craigslist",
 	}
-	if _, err := fsim.Checkout(ctx, checkoutp); err != nil {
+	if err := fsim.Checkout(ctx, checkoutp); err != nil {
 		t.Fatal(err)
 	}