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# bnkamalesh/currency

A currency computations package.
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Latest commit d6f912d Jun 1, 2019
Type Name Latest commit message Commit time
Failed to load latest commit information. .gitignore May 9, 2017 .travis.yml Jun 1, 2019 LICENSE May 9, 2017 README.md May 31, 2019 currency.go May 10, 2017 currency_test.go May 10, 2017 operations.go May 10, 2017 operations_test.go Apr 10, 2018

## Currency

Currency package helps you do currency computations accurately, by avoiding peddling. The `Currency` struct holds all the data required to define a currency.

``````type Currency struct {
// Code represents the international currency code
Code string
// Symbol is the respective currency symbol
Symbol string
// Main represents the main value of the currency
Main int
// Fractional represents the fractional/sub unit of the currency
Fractional uint
// FUName is the name of the fractional/sub unit of the currency. e.g. paise
FUName string
// FUShare represents the no.of fractional/sub units that make up 1 main unit. e.g. ₹1 = 100 paise
// Number of fractional units that make up 1 unit of the main value
FUShare uint
}
``````

### New(main int, fractional int, code, symbol string, funame string, fushare uint)

New returns a pointer of currency instance created based on the values provided

``````main - Main/Super unit of the currency
fractional - Subunit/fractional unit of the currency
code - is the currency code according to [ISO 4217 specification](https://en.wikipedia.org/wiki/ISO_4217)
symbol - Unicode symbol of the currency
funame - Name of the fractional/sub unit
fushare - Number of fractional/sub units that make up 1 unit of the main/super unit
``````

IMPORTANT! Fractional unit can be negative only when the main value is 0. If the main value is not 0, fractional unit's negative sign is ignored.

### Parsers & convenience methods

1. `NewFractional(fractional int, symbol string, fulabel string, fushare uint)` returns a currency struct instance, given a currency's total value represented by the fractional unit
2. `ParseString(value string, code, symbol string, fulabel string, fushare uint)` returns a currency struct instance, given a currency value represented as string
3. `ParseFloat64(value float64, code, symbol string, funame string, fushare uint)` returns a currency struct instance, given a currency value represented in float64

### Computational methods

IMPORTANT: Computation is supported only between same type of currencies (i.e. currency codes should be same)

1. `c1.Add(c2 currency)` add c2 to c1, and update c1
2. `c1.AddInt(main int, fractional int)` add the currency equivalent of the main & fractional int to c1
3. `c1.Subtract(c2 currency)` subtract c2 from c1, and update c1
4. `c1.SubtractIn(main int, fractional int)` subtract the currency equivalent of the main & fractional int from c1
5. `c1.Multiply(n int)` multiply c1 by n, where n is an integer
6. `c1.MultiplyFloat64(n float64)` multiply c1 by n, where n is a float64 value
7. `c1.UpdateWithFractional(ftotal int)` would update the the value of c1, where ftotal is the total value of the currency in fractional unit. e.g. INR, `UpdateWithFractional(100)` would set the main value as `1` and fractional unit as `0`
8. `c1.FractionalTotal() int` returns the total value of the currency in its fractional unit. e.g. INR, if the Main value is `1` and fractional unit is `0`, it would return `100`, i.e. 100 paise
9. `c1.Percent(n float64) currency` returns a new currency instance which is n percentage of c1
10. `c1.Divide(n int, retain bool)[]currency, ok ` returns a slice of currency of size n. `ok` if returned as `true` means the currency value was perfectly divisible by n. If `retain` is true, then `c1` will have the remainder value after dividing otherwise it is distributed among the returned currencies.

#### Why does `Divide(n int, retain bool)` return a slice of currencies?

`Divide` unlike other operations, cannot be rounded off. If it is rounded, it would result in currency peddling.

e.g. ₹1/- (INR 1) is to be divided by 3. There are 2 options of dividing this by 3.

``````1. Set 33 paise per split, and retain the remaining 1 paise at source. (`Divide(n, true)`)

2. Set 1 of the split with an extra value, i.e. 34 + 33 + 33. (`Divide(n, false)`)
``````

### Multiple currency representations

1. `c1.String(prefixSymbol bool)`, returns a string representation of the currency value. Returns string prefixed by its respective symbol if `prefixSymbol` is true
2. `c1.Float64()`, returns a float64 representation of the currency value

## Benchmarks

How to run?

`\$ go test -bench=.`

Results when run on a MacBook Pro (13-inch, Early 2015), CPU: 2.7 GHz Intel Core i5, RAM: 8 GB 1867 MHz DDR3, Graphics: Intel Iris Graphics 6100 1536 MB

``````BenchmarkNew-4                    	20000000	        67.3 ns/op
BenchmarkNewFractional-4          	20000000	        65.9 ns/op
BenchmarkParseFloat64-4           	20000000	        87.4 ns/op
BenchmarkParseString-4            	 3000000	       544 ns/op
BenchmarkString-4                 	10000000	       211 ns/op
BenchmarkStringNoPrefix-4         	10000000	       164 ns/op
BenchmarkFloat64-4                	2000000000	         0.34 ns/op
BenchmarkFractionalTotal-4        	2000000000	         0.33 ns/op
BenchmarkUpdateWithFractional-4   	100000000	        10.3 ns/op
BenchmarkAdd-4                    	100000000	        20.8 ns/op
BenchmarkAddInt-4                 	100000000	        18.9 ns/op
BenchmarkSubtract-4               	100000000	        21.2 ns/op
BenchmarkSubtractInt-4            	100000000	        18.3 ns/op
BenchmarkMultiply-4               	100000000	        16.2 ns/op
BenchmarkMultiplyFloat64-4        	50000000	        30.1 ns/op
BenchmarkPercent-4                	20000000	        67.1 ns/op
BenchmarkDivide-4                 	10000000	       155 ns/op
``````

## References

1. Ref - Sub unit or fractional unit
2. Ref - Currencies - about currencies
3. Non-decimal sub unit in currencies are only used by 2 countries today. These are getting phased out.

IMPORTANT! This package does not support sub units which are not a power of 10. Nor does it support currencies with more than 1 sub unit

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