Refactor CoinMapper

CoinMapper is now called CoinKeeper to differentiate it from
AccountMapper. A Mapper retrieves things from a store. A Keeper exposes
functionality of coins and maintain invariants.

bank.NewHandler takes a CoinKeeper instead of the entire AccountMapper.

examples/basecoin/app/init_handlers.go

@@ -25,6 +25,6 @@ func (app *BasecoinApp) initRouterHandlers() {
 
 	// All handlers must be added here.
 	// The order matters.
-	app.router.AddRoute("bank", bank.NewHandler(app.accountMapper))
+	app.router.AddRoute("bank", bank.NewHandler(bank.NewCoinKeeper(app.accountMapper)))
 	app.router.AddRoute("sketchy", sketchy.NewHandler())
 }

x/auth/mapper.go

@@ -77,6 +77,19 @@ func (am accountMapper) SetAccount(ctx sdk.Context, acc sdk.Account) {
 	store.Set(addr, bz)
 }
 
+//----------------------------------------
+// sealedAccountMapper
+
+type sealedAccountMapper struct {
+	accountMapper
+}
+
+// There's no way for external modules to mutate the
+// sam.accountMapper.ctx from here, even with reflection.
+func (sam sealedAccountMapper) WireCodec() *wire.Codec {
+	panic("accountMapper is sealed")
+}
+
 //----------------------------------------
 // misc.
 
@@ -139,16 +152,3 @@ func (am accountMapper) decodeAccount(bz []byte) sdk.Account {
 		return reflect.ValueOf(accPtr).Elem().Interface().(sdk.Account)
 	}
 }
-
-//----------------------------------------
-// sealedAccountMapper
-
-type sealedAccountMapper struct {
-	accountMapper
-}
-
-// There's no way for external modules to mutate the
-// sam.accountMapper.ctx from here, even with reflection.
-func (sam sealedAccountMapper) WireCodec() *wire.Codec {
-	panic("accountMapper is sealed")
-}

x/bank/handler.go

@@ -7,37 +7,33 @@ import (
 )
 
 // Handle all "bank" type messages.
-// NOTE: Technically, NewHandler only needs a CoinMapper
-func NewHandler(am sdk.AccountMapper) sdk.Handler {
-
+func NewHandler(ck CoinKeeper) sdk.Handler {
 	return func(ctx sdk.Context, msg sdk.Msg) sdk.Result {
-		cm := CoinMapper{am}
 		switch msg := msg.(type) {
 		case SendMsg:
-			return handleSendMsg(ctx, cm, msg)
+			return handleSendMsg(ctx, ck, msg)
 		case IssueMsg:
-			return handleIssueMsg(ctx, cm, msg)
+			return handleIssueMsg(ctx, ck, msg)
 		default:
 			errMsg := "Unrecognized bank Msg type: " + reflect.TypeOf(msg).Name()
 			return sdk.ErrUnknownRequest(errMsg).Result()
 		}
 	}
-
 }
 
 // Handle SendMsg.
-func handleSendMsg(ctx sdk.Context, cm CoinMapper, msg SendMsg) sdk.Result {
+func handleSendMsg(ctx sdk.Context, ck CoinKeeper, msg SendMsg) sdk.Result {
 	// NOTE: totalIn == totalOut should already have been checked
 
 	for _, in := range msg.Inputs {
-		_, err := cm.SubtractCoins(ctx, in.Address, in.Coins)
+		_, err := ck.SubtractCoins(ctx, in.Address, in.Coins)
 		if err != nil {
 			return err.Result()
 		}
 	}
 
 	for _, out := range msg.Outputs {
-		_, err := cm.AddCoins(ctx, out.Address, out.Coins)
+		_, err := ck.AddCoins(ctx, out.Address, out.Coins)
 		if err != nil {
 			return err.Result()
 		}
@@ -47,6 +43,6 @@ func handleSendMsg(ctx sdk.Context, cm CoinMapper, msg SendMsg) sdk.Result {
 }
 
 // Handle IssueMsg.
-func handleIssueMsg(ctx sdk.Context, cm CoinMapper, msg IssueMsg) sdk.Result {
+func handleIssueMsg(ctx sdk.Context, ck CoinKeeper, msg IssueMsg) sdk.Result {
 	panic("not implemented yet")
 }

x/bank/mapper.go

@@ -3,18 +3,24 @@ package bank
 import (
 	"fmt"
 
-	sdk "github.com/cosmos/cosmos-sdk/types"
 	crypto "github.com/tendermint/go-crypto"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
-// CoinMapper manages transfers between accounts
-type CoinMapper struct {
+// CoinKeeper manages transfers between accounts
+type CoinKeeper struct {
 	am sdk.AccountMapper
 }
 
+// NewCoinKeeper returns a new CoinKeeper
+func NewCoinKeeper(am sdk.AccountMapper) CoinKeeper {
+	return CoinKeeper{am: am}
+}
+
 // SubtractCoins subtracts amt from the coins at the addr.
-func (cm CoinMapper) SubtractCoins(ctx sdk.Context, addr crypto.Address, amt sdk.Coins) (sdk.Coins, sdk.Error) {
-	acc := cm.am.GetAccount(ctx, addr)
+func (ck CoinKeeper) SubtractCoins(ctx sdk.Context, addr crypto.Address, amt sdk.Coins) (sdk.Coins, sdk.Error) {
+	acc := ck.am.GetAccount(ctx, addr)
 	if acc == nil {
 		return amt, sdk.ErrUnrecognizedAddress(addr)
 	}
@@ -26,21 +32,21 @@ func (cm CoinMapper) SubtractCoins(ctx sdk.Context, addr crypto.Address, amt sdk
 	}
 
 	acc.SetCoins(newCoins)
-	cm.am.SetAccount(ctx, acc)
+	ck.am.SetAccount(ctx, acc)
 	return newCoins, nil
 }
 
 // AddCoins adds amt to the coins at the addr.
-func (cm CoinMapper) AddCoins(ctx sdk.Context, addr crypto.Address, amt sdk.Coins) (sdk.Coins, sdk.Error) {
-	acc := cm.am.GetAccount(ctx, addr)
+func (ck CoinKeeper) AddCoins(ctx sdk.Context, addr crypto.Address, amt sdk.Coins) (sdk.Coins, sdk.Error) {
+	acc := ck.am.GetAccount(ctx, addr)
 	if acc == nil {
-		acc = cm.am.NewAccountWithAddress(ctx, addr)
+		acc = ck.am.NewAccountWithAddress(ctx, addr)
 	}
 
 	coins := acc.GetCoins()
 	newCoins := coins.Plus(amt)
 
 	acc.SetCoins(newCoins)
-	cm.am.SetAccount(ctx, acc)
+	ck.am.SetAccount(ctx, acc)
 	return newCoins, nil
 }