Rename AmountUnit constants.

Besides being shorter, using "BTC" rather than "Bitcoin" in the
AmountUnit constants is deemed to be better for these units as BTC is
already a recognized monetary unit.

AmountBaseBitcoin has likewise been renamed to AmountSatoshi as this
is consistant with how it is returned as a string.  The "standard"
part of the comment in the const block has been removed, as Satoshi is
technically not a standard term for this unit.

ok @davecgh

amount.go

@@ -16,15 +16,15 @@ import (
 // an amount in bitcoin to an amount counted in units.
 type AmountUnit int
 
-// These constants define the various standard units used when describing
-// a bitcoin monetary amount.
+// These constants define various units used when describing a bitcoin
+// monetary amount.
 const (
-	AmountMegaBitcoin  AmountUnit = 6
-	AmountKiloBitcoin  AmountUnit = 3
-	AmountBitcoin      AmountUnit = 0
-	AmountMilliBitcoin AmountUnit = -3
-	AmountMicroBitcoin AmountUnit = -6
-	AmountBaseBitcoin  AmountUnit = -8
+	AmountMegaBTC  AmountUnit = 6
+	AmountKiloBTC  AmountUnit = 3
+	AmountBTC      AmountUnit = 0
+	AmountMilliBTC AmountUnit = -3
+	AmountMicroBTC AmountUnit = -6
+	AmountSatoshi  AmountUnit = -8
 )
 
 // String returns the unit as a string.  For recognized units, the SI
@@ -32,17 +32,17 @@ const (
 // units, "1eN BTC" is returned, where N is the AmountUnit.
 func (u AmountUnit) String() string {
 	switch u {
-	case AmountMegaBitcoin:
+	case AmountMegaBTC:
 		return "MBTC"
-	case AmountKiloBitcoin:
+	case AmountKiloBTC:
 		return "kBTC"
-	case AmountBitcoin:
+	case AmountBTC:
 		return "BTC"
-	case AmountMilliBitcoin:
+	case AmountMilliBTC:
 		return "mBTC"
-	case AmountMicroBitcoin:
+	case AmountMicroBTC:
 		return "μBTC"
-	case AmountBaseBitcoin:
+	case AmountSatoshi:
 		return "Satoshi"
 	default:
 		return "1e" + strconv.FormatInt(int64(u), 10) + " BTC"
@@ -87,13 +87,13 @@ func (a Amount) ToUnit(u AmountUnit) float64 {
 // Format formats a monetary amount counted in bitcoin base units as a
 // string for a given unit.  The conversion will succeed for any unit,
 // however, known units will be formated with an appended label describing
-// the units with SI notation.
+// the units with SI notation, or "Satoshi" for the base unit.
 func (a Amount) Format(u AmountUnit) string {
 	units := " " + u.String()
 	return strconv.FormatFloat(a.ToUnit(u), 'f', -int(u+8), 64) + units
 }
 
-// String is the equivalent of calling Format with AmountBitcoin.
+// String is the equivalent of calling Format with AmountBTC.
 func (a Amount) String() string {
-	return a.Format(AmountBitcoin)
+	return a.Format(AmountBTC)
 }

amount_test.go

@@ -118,28 +118,28 @@ func TestAmountUnitConversions(t *testing.T) {
 		{
 			name:      "MBTC",
 			amount:    Amount(MaxSatoshi),
-			unit:      AmountMegaBitcoin,
+			unit:      AmountMegaBTC,
 			converted: 21,
 			s:         "21 MBTC",
 		},
 		{
 			name:      "kBTC",
 			amount:    Amount(44433322211100),
-			unit:      AmountKiloBitcoin,
+			unit:      AmountKiloBTC,
 			converted: 444.33322211100,
 			s:         "444.333222111 kBTC",
 		},
 		{
 			name:      "BTC",
 			amount:    Amount(44433322211100),
-			unit:      AmountBitcoin,
+			unit:      AmountBTC,
 			converted: 444333.22211100,
 			s:         "444333.222111 BTC",
 		},
 		{
 			name:      "mBTC",
 			amount:    Amount(44433322211100),
-			unit:      AmountMilliBitcoin,
+			unit:      AmountMilliBTC,
 			converted: 444333222.11100,
 			s:         "444333222.111 mBTC",
 		},
@@ -147,7 +147,7 @@ func TestAmountUnitConversions(t *testing.T) {
 
 			name:      "μBTC",
 			amount:    Amount(44433322211100),
-			unit:      AmountMicroBitcoin,
+			unit:      AmountMicroBTC,
 			converted: 444333222111.00,
 			s:         "444333222111 μBTC",
 		},
@@ -155,7 +155,7 @@ func TestAmountUnitConversions(t *testing.T) {
 
 			name:      "satoshi",
 			amount:    Amount(44433322211100),
-			unit:      AmountBaseBitcoin,
+			unit:      AmountSatoshi,
 			converted: 44433322211100,
 			s:         "44433322211100 Satoshi",
 		},
@@ -183,7 +183,7 @@ func TestAmountUnitConversions(t *testing.T) {
 		}
 
 		// Verify that Amount.String works as advertised.
-		s1 := test.amount.Format(AmountBitcoin)
+		s1 := test.amount.Format(AmountBTC)
 		s2 := test.amount.String()
 		if s1 != s2 {
 			t.Errorf("%v: String does not match Format(AmountBitcoin): %v != %v", test.name, s1, s2)