google / uuid

Go package for UUIDs based on RFC 4122 and DCE 1.1: Authentication and Security Services.
BSD 3-Clause "New" or "Revised" License
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proposal: add func uuid.Compare(a, b UUID) int #152

Closed it512 closed 1 week ago

it512 commented 6 months ago

uuid is an ordered type, but Array is not supported operation < > recommended to provide a function to support comparison operations

maybe

func Compare(a, b UUID) int {
    return bytes.Compare(a[:], b[:])
}
ayang64 commented 2 weeks ago

If it doesn't exsit, adding Compare() or maybe Equal() as a method to the UUID type might be interesting too like:

if myuuid.Equal(theiruuid) {
  // do stuff
}
pborman commented 2 weeks ago

@ayang64 For equality it just is myuuid == theiruuid. Making UUIDs be comparable for equality is actually the reason that github.com/google/uuid was forked from github.com/pborman/uuid. The latter has now been rewritten to be a wrapper around the former. The former represents a UUID as an array while that latter (original) used a slice.

A Compare function (as in strings and bytes) would aid in ordering UUIDs.

@it512 Is there motivation for Compare beyond that it exists in strings and bytes?

ayang64 commented 2 weeks ago

@pborman - d'oh! thank you. i didn't consider that while i was typing.

it512 commented 2 weeks ago

sort and search for exp.

package main

import (
    "bytes"
    "log"
    "slices"

    "github.com/google/uuid"
)

func Compare(a, b uuid.UUID) int {
    return bytes.Compare(a[:], b[:])
}

var uuids = []uuid.UUID{uuid.Max, uuid.Nil, uuid.New(), uuid.New()}

func main() {
    slices.SortFunc(uuids, Compare)
    log.Println(uuids)

    i, _ := slices.BinarySearchFunc(uuids, uuid.Max, Compare)
    log.Println(i)
    log.Println(uuids[i])
}

output

2024/06/30 22:36:00 [00000000-0000-0000-0000-000000000000 c0ad65fa-53a0-44e6-b605-95b4b83d2481 f9b73b88-da50-480b-acad-f41c820b57c7 ffffffff-ffff-ffff-ffff-ffffffffffff] 2024/06/30 22:36:00 3 2024/06/30 22:36:00 ffffffff-ffff-ffff-ffff-ffffffffffff