Merge pull request #5 from govalues/int64-scale-argument

amount: Implement scale argument in Int64 method

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [0.1.1] - 2023-08-04
+
+### Changed
+
+- Implemented 'scale' argument for Amount.Int64 method.
+
 ## [0.1.0] - 2023-06-04
 
 ### Changed

amount.go

@@ -103,14 +103,13 @@ func (a Amount) Float64() (f float64, ok bool) {
 	return a.value.Float64()
 }
 
-// Int64 returns a pair of int64 values representing the integer part i and the
+// Int64 returns a pair of int64 values representing the integer part b and the
 // fractional part f of the amount.
-// The relationship can be expressed as a = i + f / 10^scale, where the scale
-// can be obtained using the [Amount.Scale] method.
+// The relationship can be expressed as a = b + f / 10^scale.
 // If the result cannot be accurately represented as a pair of int64 values,
 // the method returns false.
-func (a Amount) Int64() (i int64, f int64, ok bool) {
-	return a.value.Int64()
+func (a Amount) Int64(scale int) (b, f int64, ok bool) {
+	return a.value.Int64(scale)
 }
 
 // Prec returns the number of digits in the coefficient.
@@ -237,7 +236,7 @@ func (a Amount) Sub(b Amount) (Amount, error) {
 	d, e := a.value, b.value
 	f, err := d.SubExact(e, a.Curr().Scale())
 	if err != nil {
-		return Amount{}, fmt.Errorf("%q - %q: %w", b, a, err)
+		return Amount{}, fmt.Errorf("%q - %q: %w", a, b, err)
 	}
 	return NewAmount(a.Curr(), f)
 }
@@ -351,6 +350,7 @@ func (a Amount) Split(parts int) ([]Amount, error) {
 	}
 	ulp := rem.ULP().CopySign(rem)
 
+	// Distribute remainder
 	res := make([]Amount, parts)
 	for i := 0; i < parts; i++ {
 		res[i] = quo
@@ -365,6 +365,7 @@ func (a Amount) Split(parts int) ([]Amount, error) {
 			}
 		}
 	}
+
 	return res, nil
 }
 

doc_test.go

@@ -91,23 +91,23 @@ func (s Statement) OutgoingBalance() (money.Amount, error) {
 
 // PercChange method calculates (OutgoingBalance - IncomingBalance) / IncomingBalance
 func (s Statement) PercChange() (decimal.Decimal, error) {
-	start, err := s.IncomingBalance()
+	inc, err := s.IncomingBalance()
 	if err != nil {
 		return decimal.Decimal{}, err
 	}
-	end, err := s.OutgoingBalance()
+	out, err := s.OutgoingBalance()
 	if err != nil {
 		return decimal.Decimal{}, err
 	}
-	delta, err := end.Sub(start)
+	diff, err := out.Sub(inc)
 	if err != nil {
 		return decimal.Decimal{}, err
 	}
-	ratio, err := delta.Rat(start)
+	rat, err := diff.Rat(inc)
 	if err != nil {
 		return decimal.Decimal{}, err
 	}
-	return ratio, nil
+	return rat, nil
 }
 
 func (s Statement) TotalInterest() (money.Amount, error) {
@@ -482,16 +482,20 @@ func ExampleAmount_Float64() {
 }
 
 func ExampleAmount_Int64() {
-	a := money.MustParseAmount("JPY", "100")
-	b := money.MustParseAmount("USD", "15.60")
-	c := money.MustParseAmount("OMR", "2.389")
-	fmt.Println(a.Int64())
-	fmt.Println(b.Int64())
-	fmt.Println(c.Int64())
+	a := money.MustParseAmount("USD", "15.67")
+	fmt.Println(a.Int64(5))
+	fmt.Println(a.Int64(4))
+	fmt.Println(a.Int64(3))
+	fmt.Println(a.Int64(2))
+	fmt.Println(a.Int64(1))
+	fmt.Println(a.Int64(0))
 	// Output:
-	// 100 0 true
-	// 15 60 true
-	// 2 389 true
+	// 15 67000 true
+	// 15 6700 true
+	// 15 670 true
+	// 15 67 true
+	// 15 7 true
+	// 16 0 true
 }
 
 func ExampleAmount_Prec() {
@@ -1051,28 +1055,12 @@ func ParseMoneyProto(curr string, units int64, nanos int32) (money.Amount, error
 	if err != nil {
 		return money.Amount{}, err
 	}
-	// Units
-	if units > 0 && nanos < 0 || units < 0 && nanos > 0 {
-		return money.Amount{}, fmt.Errorf("inconsistent signs")
-	}
-	u, err := decimal.New(units, 0)
-	if err != nil {
-		return money.Amount{}, err
-	}
-	// Nanos
-	if nanos < -999_999_999 || nanos > 999_999_999 {
-		return money.Amount{}, fmt.Errorf("inconsistent nanos")
-	}
-	n, err := decimal.New(int64(nanos), 9)
-	if err != nil {
-		return money.Amount{}, err
-	}
-	n = n.Trim(c.Scale())
 	// Amount
-	d, err := u.AddExact(n, c.Scale())
+	d, err := decimal.NewFromInt64(units, int64(nanos), 9)
 	if err != nil {
 		return money.Amount{}, err
 	}
+	d = d.Trim(c.Scale())
 	return money.NewAmount(c, d)
 }
 

go.mod

@@ -2,4 +2,4 @@ module github.com/govalues/money
 
 go 1.19
 
-require github.com/govalues/decimal v0.1.0
+require github.com/govalues/decimal v0.1.4

go.sum

@@ -1,2 +1,2 @@
-github.com/govalues/decimal v0.1.0 h1:nQmM1pazhEmA3xLNn917uiealPyCYNc1vtyPXPll2Y4=
-github.com/govalues/decimal v0.1.0/go.mod h1:NfqNdX/GQBotCdmXtzckjhq54itVCX1Git3psSgom8A=
+github.com/govalues/decimal v0.1.4 h1:MbFSBjswROtTZhsK3Fvbamn2IutpMoUSqDyD8mejuFg=
+github.com/govalues/decimal v0.1.4/go.mod h1:NfqNdX/GQBotCdmXtzckjhq54itVCX1Git3psSgom8A=