simplify AppModule

CHANGELOG.md

@@ -61,6 +61,8 @@ older clients.
 
 ### API Breaking Changes
 
+* [\#6231](https://github.com/cosmos/cosmos-sdk/pull/6231) Simplify `AppModule` interface, `Route` and `NewHandler` methods become only `Route`
+and returns a new `Route` type.
 * [\#6212](https://github.com/cosmos/cosmos-sdk/pull/6212) Remove `Get*` prefixes from key construction functions
 * [\#6079](https://github.com/cosmos/cosmos-sdk/pull/6079) Remove `UpgradeOldPrivValFile` (deprecated in Tendermint Core v0.28).
 * (modules) [\#5664](https://github.com/cosmos/cosmos-sdk/pull/5664) Remove amino `Codec` from simulation `StoreDecoder`, which now returns a function closure in order to unmarshal the key-value pairs.

baseapp/baseapp_test.go

@@ -781,9 +781,9 @@ func TestCheckTx(t *testing.T) {
 	anteOpt := func(bapp *BaseApp) { bapp.SetAnteHandler(anteHandlerTxTest(t, capKey1, counterKey)) }
 	routerOpt := func(bapp *BaseApp) {
 		// TODO: can remove this once CheckTx doesnt process msgs.
-		bapp.Router().AddRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
+		bapp.Router().AddRoute(sdk.NewRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
 			return &sdk.Result{}, nil
-		})
+		}))
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)
@@ -831,7 +831,8 @@ func TestDeliverTx(t *testing.T) {
 	// test increments in the handler
 	deliverKey := []byte("deliver-key")
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, handlerMsgCounter(t, capKey1, deliverKey))
+		r := sdk.NewRoute(routeMsgCounter, handlerMsgCounter(t, capKey1, deliverKey))
+		bapp.Router().AddRoute(r)
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)
@@ -884,8 +885,10 @@ func TestMultiMsgDeliverTx(t *testing.T) {
 	deliverKey := []byte("deliver-key")
 	deliverKey2 := []byte("deliver-key2")
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, handlerMsgCounter(t, capKey1, deliverKey))
-		bapp.Router().AddRoute(routeMsgCounter2, handlerMsgCounter(t, capKey1, deliverKey2))
+		r1 := sdk.NewRoute(routeMsgCounter, handlerMsgCounter(t, capKey1, deliverKey))
+		r2 := sdk.NewRoute(routeMsgCounter2, handlerMsgCounter(t, capKey1, deliverKey2))
+		bapp.Router().AddRoute(r1)
+		bapp.Router().AddRoute(r2)
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)
@@ -960,10 +963,11 @@ func TestSimulateTx(t *testing.T) {
 	}
 
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
+		r := sdk.NewRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
 			ctx.GasMeter().ConsumeGas(gasConsumed, "test")
 			return &sdk.Result{}, nil
 		})
+		bapp.Router().AddRoute(r)
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)
@@ -1024,9 +1028,10 @@ func TestRunInvalidTransaction(t *testing.T) {
 		})
 	}
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
+		r := sdk.NewRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
 			return &sdk.Result{}, nil
 		})
+		bapp.Router().AddRoute(r)
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)
@@ -1149,11 +1154,12 @@ func TestTxGasLimits(t *testing.T) {
 	}
 
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
+		r := sdk.NewRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
 			count := msg.(msgCounter).Counter
 			ctx.GasMeter().ConsumeGas(uint64(count), "counter-handler")
 			return &sdk.Result{}, nil
 		})
+		bapp.Router().AddRoute(r)
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)
@@ -1232,11 +1238,12 @@ func TestMaxBlockGasLimits(t *testing.T) {
 	}
 
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
+		r := sdk.NewRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
 			count := msg.(msgCounter).Counter
 			ctx.GasMeter().ConsumeGas(uint64(count), "counter-handler")
 			return &sdk.Result{}, nil
 		})
+		bapp.Router().AddRoute(r)
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)
@@ -1317,9 +1324,10 @@ func TestCustomRunTxPanicHandler(t *testing.T) {
 		})
 	}
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
+		r := sdk.NewRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
 			return &sdk.Result{}, nil
 		})
+		bapp.Router().AddRoute(r)
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)
@@ -1356,7 +1364,8 @@ func TestBaseAppAnteHandler(t *testing.T) {
 
 	deliverKey := []byte("deliver-key")
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, handlerMsgCounter(t, capKey1, deliverKey))
+		r := sdk.NewRoute(routeMsgCounter, handlerMsgCounter(t, capKey1, deliverKey))
+		bapp.Router().AddRoute(r)
 	}
 
 	cdc := codec.New()
@@ -1451,11 +1460,12 @@ func TestGasConsumptionBadTx(t *testing.T) {
 	}
 
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
+		r := sdk.NewRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
 			count := msg.(msgCounter).Counter
 			ctx.GasMeter().ConsumeGas(uint64(count), "counter-handler")
 			return &sdk.Result{}, nil
 		})
+		bapp.Router().AddRoute(r)
 	}
 
 	cdc := codec.New()
@@ -1504,11 +1514,12 @@ func TestQuery(t *testing.T) {
 	}
 
 	routerOpt := func(bapp *BaseApp) {
-		bapp.Router().AddRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
+		r := sdk.NewRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
 			store := ctx.KVStore(capKey1)
 			store.Set(key, value)
 			return &sdk.Result{}, nil
 		})
+		bapp.Router().AddRoute(r)
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)
@@ -1639,8 +1650,8 @@ type testCustomRouter struct {
 	routes sync.Map
 }
 
-func (rtr *testCustomRouter) AddRoute(path string, h sdk.Handler) sdk.Router {
-	rtr.routes.Store(path, h)
+func (rtr *testCustomRouter) AddRoute(route *sdk.Route) sdk.Router {
+	rtr.routes.Store(route.Path(), route.Handler())
 	return rtr
 }
 
@@ -1662,7 +1673,8 @@ func TestWithRouter(t *testing.T) {
 	deliverKey := []byte("deliver-key")
 	routerOpt := func(bapp *BaseApp) {
 		bapp.SetRouter(&testCustomRouter{routes: sync.Map{}})
-		bapp.Router().AddRoute(routeMsgCounter, handlerMsgCounter(t, capKey1, deliverKey))
+		r := sdk.NewRoute(routeMsgCounter, handlerMsgCounter(t, capKey1, deliverKey))
+		bapp.Router().AddRoute(r)
 	}
 
 	app := setupBaseApp(t, anteOpt, routerOpt)

baseapp/router.go

@@ -21,15 +21,15 @@ func NewRouter() *Router {
 
 // AddRoute adds a route path to the router with a given handler. The route must
 // be alphanumeric.
-func (rtr *Router) AddRoute(path string, h sdk.Handler) sdk.Router {
-	if !sdk.IsAlphaNumeric(path) {
+func (rtr *Router) AddRoute(route *sdk.Route) sdk.Router {
+	if !sdk.IsAlphaNumeric(route.Path()) {
 		panic("route expressions can only contain alphanumeric characters")
 	}
-	if rtr.routes[path] != nil {
-		panic(fmt.Sprintf("route %s has already been initialized", path))
+	if rtr.routes[route.Path()] != nil {
+		panic(fmt.Sprintf("route %s has already been initialized", route.Path()))
 	}
 
-	rtr.routes[path] = h
+	rtr.routes[route.Path()] = route.Handler()
 	return rtr
 }
 

baseapp/router_test.go

@@ -17,15 +17,15 @@ func TestRouter(t *testing.T) {
 
 	// require panic on invalid route
 	require.Panics(t, func() {
-		rtr.AddRoute("*", testHandler)
+		rtr.AddRoute(sdk.NewRoute("*", testHandler))
 	})
 
-	rtr.AddRoute("testRoute", testHandler)
+	rtr.AddRoute(sdk.NewRoute("testRoute", testHandler))
 	h := rtr.Route(sdk.Context{}, "testRoute")
 	require.NotNil(t, h)
 
 	// require panic on duplicate route
 	require.Panics(t, func() {
-		rtr.AddRoute("testRoute", testHandler)
+		rtr.AddRoute(sdk.NewRoute("testRoute", testHandler))
 	})
 }

docs/building-modules/handler.md

@@ -28,8 +28,8 @@ Let us break it down:
 
 Module `handler`s are typically implemented in a `./handler.go` file inside the module's folder. The
 [module manager](./module-manager.md) is used to add the module's `handler`s to the
-[application's `router`](../core/baseapp.md#message-routing) via the `NewHandler()` method. Typically,
-the manager's `NewHandler()` method simply calls a `NewHandler()` method defined in `handler.go`,
+[application's `router`](../core/baseapp.md#message-routing) via the `Route()` method. Typically,
+the manager's `Route()` method simply constructs a Route that calls a `NewHandler()` method defined in `handler.go`,
 which looks like the following:
 
 ```go

docs/building-modules/module-manager.md

@@ -67,8 +67,7 @@ The `AppModule` interface defines the inter-dependent methods modules need to im
 Let us go through the methods of `AppModule`:
 
 - `RegisterInvariants(sdk.InvariantRegistry)`: Registers the [`invariants`](./invariants.md) of the module. If the invariants deviates from its predicted value, the [`InvariantRegistry`](./invariants.md#registry) triggers appropriate logic (most often the chain will be halted). 
-- `Route()`: Returns the name of the module's route, for [`message`s](./messages-and-queries.md#messages) to be routed to the module by [`baseapp`](../core/baseapp.md#message-routing).
-- `NewHandler()`: Returns a [`handler`](./handler.md) given the `Type()` of the `message`, in order to process the `message`. 
+- `Route()`: Returns the route for [`message`s](./messages-and-queries.md#messages) to be routed to the module by [`baseapp`](../core/baseapp.md#message-routing).
 - `QuerierRoute()`: Returns the name of the module's query route, for [`queries`](./messages-and-queries.md#queries) to be routes to the module by [`baseapp`](../core/baseapp.md#query-routing). 
 - `NewQuerierHandler()`: Returns a [`querier`](./querier.md) given the query `path`, in order to process the `query`. 
 - `BeginBlock(sdk.Context, abci.RequestBeginBlock)`: This method gives module developers the option to implement logic that is automatically triggered at the beginning of each block. Implement empty if no logic needs to be triggered at the beginning of each block for this module. 
@@ -78,7 +77,7 @@ Let us go through the methods of `AppModule`:
 
 Typically, the various application module interfaces are implemented in a file called `module.go`, located in the module's folder (e.g. `./x/module/module.go`). 
 
-Almost every module need to implement the `AppModuleBasic` and `AppModule` interfaces. If the module is only used for genesis, it will implement `AppModuleGenesis` instead of `AppModule`. The concrete type that implements the interface can add parameters that are required for the implementation of the various methods of the interface. For example, the `NewHandler()`  function often calls a `NewHandler(k keeper)` function defined in [`handler.go`](./handler.md) and therefore needs to pass the module's [`keeper`](./keeper.md) as parameter. 
+Almost every module need to implement the `AppModuleBasic` and `AppModule` interfaces. If the module is only used for genesis, it will implement `AppModuleGenesis` instead of `AppModule`. The concrete type that implements the interface can add parameters that are required for the implementation of the various methods of the interface. For example, the `Route()`  function often calls a `NewHandler(k keeper)` function defined in [`handler.go`](./handler.md) and therefore needs to pass the module's [`keeper`](./keeper.md) as parameter. 
 
 ```go
 // example

server/mock/app.go

@@ -36,8 +36,8 @@ func NewApp(rootDir string, logger log.Logger) (abci.Application, error) {
 
 	baseApp.SetInitChainer(InitChainer(capKeyMainStore))
 
-	// Set a handler Route.
-	baseApp.Router().AddRoute("kvstore", KVStoreHandler(capKeyMainStore))
+	// Set a Route.
+	baseApp.Router().AddRoute(sdk.NewRoute("kvstore", KVStoreHandler(capKeyMainStore)))
 
 	// Load latest version.
 	if err := baseApp.LoadLatestVersion(); err != nil {

types/module/module.go

@@ -141,8 +141,7 @@ type AppModule interface {
 	RegisterInvariants(sdk.InvariantRegistry)
 
 	// routes
-	Route() string
-	NewHandler() sdk.Handler
+	Route() *sdk.Route
 	// Deprecated: use RegisterQueryService
 	QuerierRoute() string
 	// Deprecated: use RegisterQueryService
@@ -173,10 +172,7 @@ func NewGenesisOnlyAppModule(amg AppModuleGenesis) AppModule {
 func (GenesisOnlyAppModule) RegisterInvariants(_ sdk.InvariantRegistry) {}
 
 // Route empty module message route
-func (GenesisOnlyAppModule) Route() string { return "" }
-
-// NewHandler returns an empty module handler
-func (GenesisOnlyAppModule) NewHandler() sdk.Handler { return nil }
+func (GenesisOnlyAppModule) Route() *sdk.Route { return nil }
 
 // QuerierRoute returns an empty module querier route
 func (GenesisOnlyAppModule) QuerierRoute() string { return "" }
@@ -255,8 +251,8 @@ func (m *Manager) RegisterInvariants(ir sdk.InvariantRegistry) {
 // RegisterRoutes registers all module routes and module querier routes
 func (m *Manager) RegisterRoutes(router sdk.Router, queryRouter sdk.QueryRouter) {
 	for _, module := range m.Modules {
-		if module.Route() != "" {
-			router.AddRoute(module.Route(), module.NewHandler())
+		if module.Route() != nil {
+			router.AddRoute(module.Route())
 		}
 		if module.QuerierRoute() != "" {
 			queryRouter.AddRoute(module.QuerierRoute(), module.NewQuerierHandler())

types/module/module_test.go

@@ -69,9 +69,8 @@ func TestGenesisOnlyAppModule(t *testing.T) {
 	mockInvariantRegistry := mocks.NewMockInvariantRegistry(mockCtrl)
 	goam := module.NewGenesisOnlyAppModule(mockModule)
 
-	require.Empty(t, goam.Route())
+	require.Nil(t, goam.Route())
 	require.Empty(t, goam.QuerierRoute())
-	require.Nil(t, goam.NewHandler())
 	require.Nil(t, goam.NewQuerierHandler())
 
 	// no-op
@@ -142,12 +141,10 @@ func TestManager_RegisterRoutes(t *testing.T) {
 
 	router := mocks.NewMockRouter(mockCtrl)
 	handler1, handler2 := sdk.Handler(nil), sdk.Handler(nil)
-	mockAppModule1.EXPECT().Route().Times(2).Return("route1")
-	mockAppModule2.EXPECT().Route().Times(2).Return("route2")
-	mockAppModule1.EXPECT().NewHandler().Times(1).Return(handler1)
-	mockAppModule2.EXPECT().NewHandler().Times(1).Return(handler2)
-	router.EXPECT().AddRoute(gomock.Eq("route1"), gomock.Eq(handler1)).Times(1)
-	router.EXPECT().AddRoute(gomock.Eq("route2"), gomock.Eq(handler2)).Times(1)
+	mockAppModule1.EXPECT().Route().Times(2).Return(sdk.NewRoute("route1", handler1))
+	mockAppModule2.EXPECT().Route().Times(2).Return(sdk.NewRoute("route2", handler2))
+	router.EXPECT().AddRoute(gomock.Eq(sdk.NewRoute("route1", handler1))).Times(1)
+	router.EXPECT().AddRoute(gomock.Eq(sdk.NewRoute("route2", handler2))).Times(1)
 
 	queryRouter := mocks.NewMockQueryRouter(mockCtrl)
 	mockAppModule1.EXPECT().QuerierRoute().Times(2).Return("querierRoute1")

types/router.go

@@ -26,10 +26,27 @@ var (
 
 // Router provides handlers for each transaction type.
 type Router interface {
-	AddRoute(r string, h Handler) Router
+	AddRoute(r *Route) Router
 	Route(ctx Context, path string) Handler
 }
 
+type Route struct {
+	path    string
+	handler Handler
+}
+
+func NewRoute(p string, h Handler) *Route {
+	return &Route{path: p, handler: h}
+}
+
+func (r Route) Path() string {
+	return r.path
+}
+
+func (r Route) Handler() Handler {
+	return r.handler
+}
+
 // QueryRouter provides queryables for each query path.
 type QueryRouter interface {
 	AddRoute(r string, h Querier) QueryRouter