Is there an opposite of include for Ruby Arrays

Question

I ve got the following logic in my code   if   players include  p name        end    players is an array   Is there a method so I can avoid the     Ideally  this snippet would be   if  players does not include  p name        end

User · Answer

Can you use   unless  players include  p name  do     end   unless is opposite of if  or you may use reject   You can reject the not-required elements    players reject  x  x  p name    after the getting the results you can do your implementation

User · Answer

Using unless is fine for statements with single include  clauses but  for example  when you need to check the inclusion of something in one Array but not in another  the use of include  with exclude  is much friendlier   if  players include   amp  amp   spectators exclude  do        end   But as dizzy42 says above  the use of exclude  requires ActiveSupport

User · Answer

Here you go   unless  players include  p name        end   You might have a look at the Ruby Style Guide for more info on similar techniques

User · Answer

if  players exclude  p name          end   ActiveSupport adds the exclude  method to Array  Hash  and String   This is not pure Ruby  but is used by a LOT of rubyists   Source  Active Support Core Extensions  Rails Guides

User · Answer

I was looking up on this for myself  found this  and then a solution  People are using confusing methods and some methods that don t work in certain situations or not at all   I know it s too late now  considering this was posted 6 years ago  but hopefully future visitors find this  and hopefully  it can clean up their  and your  code    Simple solution   if not  players include  p name  do        end

User · Answer

Looking at Ruby only   TL DR  Use none  passing it a block with    for the comparison    1  2  include  1       gt  true  1  2  none     n  1    n         gt  false     Array include  accepts one argument and uses    to check against each element in the array   player    1  2  3  player include  1      gt  true   Enumerable none  can also accept one argument in which case it uses     for the comparison  To get the opposing behaviour to include  we omit the parameter and pass it a block using    for the comparison   player none     n  7    n       gt  true   player include  7      notice the         gt  true   In the above example we can actually use   player none  7      gt  true   That s because Integer    and Integer     are equivalent  But consider   player include  Integer      gt  false player none  Integer      gt  false   none  returns false because Integer     1    gt  true  But really a legit notinclude  method should return true  So as we did before   player none     e  Integer    e        gt  true

User · Answer

Use unless   unless  players include  p name  do       end

User · Answer

How about the following   unless  players include  p name         end

User · Answer

Try something like this     players include  p name    false   true

User · Answer

module Enumerable   def does not include  item       include  item    end end   Ok  but seriously  the unless works fine

User · Answer

Try this  it s pure Ruby so there s no need to add any peripheral frameworks  if  players include  p name     false do        end   I was struggling with a similar logic for a few days  and after checking several forums and Q amp A boards to little avail it turns out the solution was actually pretty simple

[ruby-on-rails] Is there an opposite of include? for Ruby Arrays?

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