Price Module

The price module defines value objects to deal with prices and charges. The following types exist:

Price: Represents simply a money value. See below for more details. For example: 5€
Charge: Represents a Price together with its Type. This is used to describe that something need to be paid in a certain currency and represents a certain value. For example it might be you need (or want) to pay the value of 5€ in 500 Loyaltypoints. This can be described in the Charge Type.
Charges: Is a list of the type Charge. For example to indicate that you are paying to value of 5€ with two Charges: 2€ and 300 Loyaltypoints

Price Type:

The price module offers a Price Type with useful methods.

Price calculation is not a trivial topic and multiple solutions exist. The implementation details of the price object is:

internally we use big.Float to hold the amount, this is to be able to calculate exactly
however, a float like representation of an amount cannot be paid, that is why the price has a method "GetPayablePrice" that returns a Price that can be paid in the given currency, using correct rounding and amount representation

Example:

// get 2.45 EUR Price
price := NewFromInt(245,100,"EUR")

rowPrice := price.Multiply(10)

// 10% discount
discountedRowPrice := rowPrice.Discounted(10.0)

// What needs to be paid:
priceToPay := discountedRowPrice.GetPayable()

// what needs to be paid by item()
singleItemsPrices := discountedRowPrice.SplitInPayables(10)

// you can also set price from float:
price2 := NewFromFloat(2.45,"EUR")

Be aware that price.Equals(price2) may be false but due to float arithmetic but price.GetPayable().Equals(price2.GetPayable()) will be true

Rounding Modes

We support a variety of rounding modes. These can be used with the GetPayableByRoundingMode function by specifying a mode and precision. The following modes are available:

RoundingModeFloor

Rounding mode to round towards negative infinity. Note that this rounding mode never increases the calculated value.

price price.GetPayableByRoundingMode(RoundingModeFloor, 1)

5.5 5

2.5 2

1.6 1

1.1 1

1.0 1

-1.0 -1

-1.1 -2

-1.6 -2

-2.5 -3

-5.5 -6
RoundingModeCeil

Rounding mode to round towards positive infinity. Note that this rounding mode never decreases the calculated value.

price price.GetPayableByRoundingMode(RoundingModeCeil, 1)

5.5 6

2.5 3

1.6 2

1.1 2

1.0 1

-1.0 -1

-1.1 -1

-1.6 -1

-2.5 -2

-5.5 -5
RoundingModeHalfUp default mode for GetPayable()

Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up. Note that this is the rounding mode commonly taught at school.

price price.GetPayableByRoundingMode(RoundingModeHalfUp, 1)

5.5 6

2.5 3

1.6 2

1.1 1

1.0 1

-1.0 -1

-1.1 -1

-1.6 -2

-2.5 -3

-5.5 -6
RoundingModeHalfDown

Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down.

price price.GetPayableByRoundingMode(RoundingModeHalfDown, 1)

5.5 5

2.5 2

1.6 2

1.1 1

1.0 1

-1.0 -1

-1.1 -1

-1.6 -2

-2.5 -2

-5.5 -5

`price`	`price.GetPayableByRoundingMode(RoundingModeFloor, 1)`
5.5	5
2.5	2
1.6	1
1.1	1
1.0	1
-1.0	-1
-1.1	-2
-1.6	-2
-2.5	-3
-5.5	-6

`price`	`price.GetPayableByRoundingMode(RoundingModeCeil, 1)`
5.5	6
2.5	3
1.6	2
1.1	2
1.0	1
-1.0	-1
-1.1	-1
-1.6	-1
-2.5	-2
-5.5	-5

`price`	`price.GetPayableByRoundingMode(RoundingModeHalfUp, 1)`
5.5	6
2.5	3
1.6	2
1.1	1
1.0	1
-1.0	-1
-1.1	-1
-1.6	-2
-2.5	-3
-5.5	-6

`price`	`price.GetPayableByRoundingMode(RoundingModeHalfDown, 1)`
5.5	5
2.5	2
1.6	2
1.1	1
1.0	1
-1.0	-1
-1.1	-1
-1.6	-2
-2.5	-2
-5.5	-5

Charge:

Represents a price together with a type. A charge has a values price (normally in default currency) and a the price that is paid that might be in a different currency. Can be used in places where you need to give the price value a certain extra semantic information or to represent something that need to be paid (charged).

Template Func - Formatting a Price Object