Delete known element from slice in Go

Question

I am trying to use the slices package to delete a chan []byte from a slice of them. But I have a known value that I want to remove instead of using the position like it shows here How to delete an element from a Slice in Golang.

import "golang.org/x/exp/slices"

var receiverChannels []chan []byte

channel := make(chan []byte)
receiverChannels = append(receiverChannels, channel)

receiverChannels = slices.Delete(receiverChannels, channel)

Answer 1

Go 1.18 solution with type parameters:

func Delete[T comparable](collection []T, el T) []T {
    idx := Find(collection, el)
    if idx > -1 {
        return slices.Delete(collection, idx, idx+1)
    }
    return collection
}

func Find[T comparable](collection []T, el T) int {
    for i := range collection {
        if collection[i] == el {
            return i
        }
    }
    return -1
}

Answer 2

If the ordering of the slice is not important, you can use a map instead:

var receiverChannels = make(map[chan []byte]struct{})

channel:=make(chan []byte)
receiverChannels[channel]=struct{}{}
delete(receiverChannels,channel)

Otherwise, you need a find helper function:

func find(channels []chan []byte, ch chan []byte) int {
   for i:=range channels {
     if channels[i]==ch {
        return i
     }
   }
  return -1
}

Or a generic find:

func find[T comparable](slice []T, item T) int {
    for i := range slice {
        if slice[i] == item {
            return i
        }
    }
    return -1
}

If you need to keep a slice but ordering is not important, you can simply move the last element and truncate the slice:

i:=find(receiverChannels, channel)
if i!=-1 {
  if i<len(receiverChannels)-1 {
    receiverChannels[i]=receiverChannels[len(receiverChannels)-1]
  }
  receiverChannels=receiverChannels[:len(receiverChannels)-1]
}

Last, if ordering is important:

i:=find(receiverChannels, channel)
if i!=-1 {
   receiverChannels=append(receiverChannels[:i], receiverChannels[i+1:]...)
   receiverChannels=receiverChannels[:len(receiverChannels)-1]
}