GoToSocial/vendor/github.com/shopspring/decimal
Vyr Cossont fc3741365c
[bugfix] Fix Swagger spec and add test script (#2698)
* Add Swagger spec test script

* Fix Swagger spec errors not related to statuses with polls

* Add API tests that post a status with a poll

* Fix creating a status with a poll from form params

* Fix Swagger spec errors related to statuses with polls (this is the last error)

* Fix Swagger spec warnings not related to unused definitions

* Suppress a duplicate list update params definition that was somehow causing wrong param names

* Add Swagger test to CI

- updates Drone config
- vendorizes go-swagger
- fixes a file extension issue that caused the test script to generate JSON instead of YAML with the vendorized version

* Put `Sample: ` on its own line everywhere

* Remove unused id param from emojiCategoriesGet

* Add 5 more pairs of profile fields to account update API Swagger

* Remove Swagger prefix from dummy fields

It makes the generated code look weird

* Manually annotate params for statusCreate operation

* Fix all remaining Swagger spec warnings

- Change some models into operation parameters
- Ignore models that already correspond to manually documented operation parameters but can't be trivially changed (those with file fields)

* Documented that creating a status with scheduled_at isn't implemented yet

* sign drone.yml

* Fix filter API Swagger errors

* fixup! Fix filter API Swagger errors

---------

Co-authored-by: tobi <tobi.smethurst@protonmail.com>
2024-03-06 18:05:45 +01:00
..
.gitignore [bugfix] Fix Swagger spec and add test script (#2698) 2024-03-06 18:05:45 +01:00
.travis.yml [bugfix] Fix Swagger spec and add test script (#2698) 2024-03-06 18:05:45 +01:00
CHANGELOG.md [bugfix] Fix Swagger spec and add test script (#2698) 2024-03-06 18:05:45 +01:00
LICENSE [bugfix] Fix Swagger spec and add test script (#2698) 2024-03-06 18:05:45 +01:00
README.md [bugfix] Fix Swagger spec and add test script (#2698) 2024-03-06 18:05:45 +01:00
decimal-go.go [bugfix] Fix Swagger spec and add test script (#2698) 2024-03-06 18:05:45 +01:00
decimal.go [bugfix] Fix Swagger spec and add test script (#2698) 2024-03-06 18:05:45 +01:00
rounding.go [bugfix] Fix Swagger spec and add test script (#2698) 2024-03-06 18:05:45 +01:00

README.md

decimal

Build Status GoDoc Go Report Card

Arbitrary-precision fixed-point decimal numbers in go.

Note: Decimal library can "only" represent numbers with a maximum of 2^31 digits after the decimal point.

Features

  • The zero-value is 0, and is safe to use without initialization
  • Addition, subtraction, multiplication with no loss of precision
  • Division with specified precision
  • Database/sql serialization/deserialization
  • JSON and XML serialization/deserialization

Install

Run go get github.com/shopspring/decimal

Requirements

Decimal library requires Go version >=1.7

Usage

package main

import (
	"fmt"
	"github.com/shopspring/decimal"
)

func main() {
	price, err := decimal.NewFromString("136.02")
	if err != nil {
		panic(err)
	}

	quantity := decimal.NewFromInt(3)

	fee, _ := decimal.NewFromString(".035")
	taxRate, _ := decimal.NewFromString(".08875")

	subtotal := price.Mul(quantity)

	preTax := subtotal.Mul(fee.Add(decimal.NewFromFloat(1)))

	total := preTax.Mul(taxRate.Add(decimal.NewFromFloat(1)))

	fmt.Println("Subtotal:", subtotal)                      // Subtotal: 408.06
	fmt.Println("Pre-tax:", preTax)                         // Pre-tax: 422.3421
	fmt.Println("Taxes:", total.Sub(preTax))                // Taxes: 37.482861375
	fmt.Println("Total:", total)                            // Total: 459.824961375
	fmt.Println("Tax rate:", total.Sub(preTax).Div(preTax)) // Tax rate: 0.08875
}

Documentation

http://godoc.org/github.com/shopspring/decimal

Production Usage

  • Spring, since August 14, 2014.
  • If you are using this in production, please let us know!

FAQ

Why don't you just use float64?

Because float64 (or any binary floating point type, actually) can't represent numbers such as 0.1 exactly.

Consider this code: http://play.golang.org/p/TQBd4yJe6B You might expect that it prints out 10, but it actually prints 9.999999999999831. Over time, these small errors can really add up!

Why don't you just use big.Rat?

big.Rat is fine for representing rational numbers, but Decimal is better for representing money. Why? Here's a (contrived) example:

Let's say you use big.Rat, and you have two numbers, x and y, both representing 1/3, and you have z = 1 - x - y = 1/3. If you print each one out, the string output has to stop somewhere (let's say it stops at 3 decimal digits, for simplicity), so you'll get 0.333, 0.333, and 0.333. But where did the other 0.001 go?

Here's the above example as code: http://play.golang.org/p/lCZZs0w9KE

With Decimal, the strings being printed out represent the number exactly. So, if you have x = y = 1/3 (with precision 3), they will actually be equal to 0.333, and when you do z = 1 - x - y, z will be equal to .334. No money is unaccounted for!

You still have to be careful. If you want to split a number N 3 ways, you can't just send N/3 to three different people. You have to pick one to send N - (2/3*N) to. That person will receive the fraction of a penny remainder.

But, it is much easier to be careful with Decimal than with big.Rat.

Why isn't the API similar to big.Int's?

big.Int's API is built to reduce the number of memory allocations for maximal performance. This makes sense for its use-case, but the trade-off is that the API is awkward and easy to misuse.

For example, to add two big.Ints, you do: z := new(big.Int).Add(x, y). A developer unfamiliar with this API might try to do z := a.Add(a, b). This modifies a and sets z as an alias for a, which they might not expect. It also modifies any other aliases to a.

Here's an example of the subtle bugs you can introduce with big.Int's API: https://play.golang.org/p/x2R_78pa8r

In contrast, it's difficult to make such mistakes with decimal. Decimals behave like other go numbers types: even though a = b will not deep copy b into a, it is impossible to modify a Decimal, since all Decimal methods return new Decimals and do not modify the originals. The downside is that this causes extra allocations, so Decimal is less performant. My assumption is that if you're using Decimals, you probably care more about correctness than performance.

License

The MIT License (MIT)

This is a heavily modified fork of fpd.Decimal, which was also released under the MIT License.