more app1/app2 cleanup

docs/core/app1.md

@@ -229,41 +229,6 @@ us to easily lookup transactions that pertain to particular accounts or actions.
 
 Let's define our handler for App1:
 
-```go
-func NewApp1Handler(keyAcc *sdk.KVStoreKey) sdk.Handler {
-	return func(ctx sdk.Context, msg sdk.Msg) sdk.Result {
-		switch msg := msg.(type) {
-		case MsgSend:
-			return handleMsgSend(ctx, keyAcc, msg)
-		default:
-			errMsg := "Unrecognized bank Msg type: " + reflect.TypeOf(msg).Name()
-			return sdk.ErrUnknownRequest(errMsg).Result()
-		}
-	}
-}
-```
-
-We have only a single message type, so just one message-specific function to define, `handleMsgSend`.
-
-Note this handler has unrestricted access to the store specified by the capability key `keyAcc`,
-so it must define what to store and how to encode it. Later, we'll introduce
-higher-level abstractions so Handlers are restricted in what they can do.
-For this first example, we use a simple account that is JSON encoded:
-
-```go
-type appAccount struct {
-	Coins sdk.Coins `json:"coins"`
-}
-```
-
-Coins is a useful type provided by the SDK for multi-asset accounts. 
-We could just use an integer here for a single coin type, but
-it's worth [getting to know
-Coins](https://godoc.org/github.com/cosmos/cosmos-sdk/types#Coins).
-
-
-Now we're ready to handle the MsgSend:
-
 ```go
 // Handle MsgSend.
 // NOTE: msg.From, msg.To, and msg.Amount were already validated
@@ -290,10 +255,26 @@ func handleMsgSend(ctx sdk.Context, key *sdk.KVStoreKey, msg MsgSend) sdk.Result
 }
 ```
 
-The handler is straight forward. We first load the KVStore from the context using the granted capability key.
+We have only a single message type, so just one message-specific function to define, `handleMsgSend`.
-Then we make two state transitions: one for the sender, one for the receiver. 
+
-Each one involves JSON unmarshalling the account bytes from the store, mutating
+Note this handler has unrestricted access to the store specified by the capability key `keyAcc`,
-the `Coins`, and JSON marshalling back into the store:
+so it must define what to store and how to encode it. Later, we'll introduce
+higher-level abstractions so Handlers are restricted in what they can do.
+For this first example, we use a simple account that is JSON encoded:
+
+```go
+type appAccount struct {
+	Coins sdk.Coins `json:"coins"`
+}
+```
+
+Coins is a useful type provided by the SDK for multi-asset accounts. 
+We could just use an integer here for a single coin type, but
+it's worth [getting to know
+Coins](https://godoc.org/github.com/cosmos/cosmos-sdk/types#Coins).
+
+
+Now we're ready to handle the two parts of the MsgSend:
 
 ```go
 func handleFrom(store sdk.KVStore, from sdk.Address, amt sdk.Coins) sdk.Result {
@@ -367,6 +348,11 @@ func handleTo(store sdk.KVStore, to sdk.Address, amt sdk.Coins) sdk.Result {
 }
 ```
 
+The handler is straight forward. We first load the KVStore from the context using the granted capability key.
+Then we make two state transitions: one for the sender, one for the receiver. 
+Each one involves JSON unmarshalling the account bytes from the store, mutating
+the `Coins`, and JSON marshalling back into the store.
+
 And that's that!
 
 ## Tx

docs/core/app2.md

@@ -74,24 +74,36 @@ func handleMsgIssue(keyIssue *sdk.KVStoreKey, keyAcc *sdk.KVStoreKey) sdk.Handle
 func handleIssuer(store sdk.KVStore, issuer sdk.Address, coin sdk.Coin) sdk.Result {
 	// the issuer address is stored directly under the coin denomination
 	denom := []byte(coin.Denom)
-	issuerAddress := store.Get(denom)
+	infoBytes := store.Get(denom)
-	if issuerAddress == nil {
+	if infoBytes == nil {
 		return sdk.ErrInvalidCoins(fmt.Sprintf("Unknown coin type %s", coin.Denom)).Result()
 	}
 
+	var coinInfo coinInfo
+	err := json.Unmarshal(infoBytes, &coinInfo)
+	if err != nil {
+		return sdk.ErrInternal("Error when deserializing coinInfo").Result()
+	}
+
 	// Msg Issuer is not authorized to issue these coins
-	if !bytes.Equal(issuerAddress, issuer) {
+	if !bytes.Equal(coinInfo.Issuer, issuer) {
 		return sdk.ErrUnauthorized(fmt.Sprintf("Msg Issuer cannot issue tokens: %s", coin.Denom)).Result()
 	}
 
 	return sdk.Result{}
 }
+
+// coinInfo stores meta data about a coin
+type coinInfo struct {
+	Issuer sdk.Address `json:"issuer"`
+}
 ```
 
-Note we're just storing the issuer address for each coin directly under the
+Note we've introduced the `coinInfo` type to store the issuer address for each coin.
-coin's denomination in the issuer store. We could of course use a struct with more
+We JSON serialize this type and store it directly under the denomination in the
-fields, like the current supply of coins in existence, and the maximum supply
+issuer store. We could of course add more fields and logic around this,
-allowed to be issued.
+like including the current supply of coins in existence, and enforcing a maximum supply,
+but that's left as an excercise for the reader :).
 
 ## Amino
 

docs/core/examples/app2.go

@@ -117,7 +117,7 @@ func (msg MsgIssue) Tags() sdk.Tags {
 //------------------------------------------------------------------
 // Handler for the message
 
-// Handle MsgIssue
+// Handle MsgIssue.
 func handleMsgIssue(keyIssue *sdk.KVStoreKey, keyAcc *sdk.KVStoreKey) sdk.Handler {
 	return func(ctx sdk.Context, msg sdk.Msg) sdk.Result {
 		issueMsg, ok := msg.(MsgIssue)
@@ -149,19 +149,30 @@ func handleMsgIssue(keyIssue *sdk.KVStoreKey, keyAcc *sdk.KVStoreKey) sdk.Handle
 func handleIssuer(store sdk.KVStore, issuer sdk.Address, coin sdk.Coin) sdk.Result {
 	// the issuer address is stored directly under the coin denomination
 	denom := []byte(coin.Denom)
-	issuerAddress := store.Get(denom)
+	infoBytes := store.Get(denom)
-	if issuerAddress == nil {
+	if infoBytes == nil {
 		return sdk.ErrInvalidCoins(fmt.Sprintf("Unknown coin type %s", coin.Denom)).Result()
 	}
 
+	var coinInfo coinInfo
+	err := json.Unmarshal(infoBytes, &coinInfo)
+	if err != nil {
+		return sdk.ErrInternal("Error when deserializing coinInfo").Result()
+	}
+
 	// Msg Issuer is not authorized to issue these coins
-	if !bytes.Equal(issuerAddress, issuer) {
+	if !bytes.Equal(coinInfo.Issuer, issuer) {
 		return sdk.ErrUnauthorized(fmt.Sprintf("Msg Issuer cannot issue tokens: %s", coin.Denom)).Result()
 	}
 
 	return sdk.Result{}
 }
 
+// coinInfo stores meta data about a coin
+type coinInfo struct {
+	Issuer sdk.Address `json:"issuer"`
+}
+
 //------------------------------------------------------------------
 // Tx