How to check if a Ruby object is a Boolean

Question

I can t seem to check if an object is a boolean easily   Is there something like this in Ruby   true is a  Boolean  false is a  Boolean    Right now I m doing this and would like to shorten it   some var   rand 1     1   true   false  some var is a  TrueClass     some var is a  FalseClass

User · Accepted Answer

Simplest way I can think of     checking whether foo is a boolean   foo    foo

User · Answer

This gem adds a Boolean class to Ruby with useful methods   https   github com RISCfuture boolean  Use   require  boolean    Then your  true is a  Boolean  false is a  Boolean    will work exactly as you expect

User · Answer

As stated above there is no boolean class just TrueClass and FalseClass however you can use any object as the subject of if unless and everything is true except instances of FalseClass and nil  Boolean tests return an instance of the FalseClass or TrueClass   1  gt  0  class  TrueClass   The following monkeypatch to Object will tell you whether something is an instance of TrueClass or FalseClass  class Object   def boolean      self is a  TrueClass     self is a  FalseClass     end end   Running some tests with irb gives the following results    gt   String  boolean    gt  false  gt  gt  1 boolean    gt  false  gt  gt  Time now boolean    gt  false  gt  gt  nil boolean    gt  false  gt  gt  true boolean    gt  true  gt  gt  false boolean    gt  true  gt  gt   1   1  boolean    gt  true  gt  gt   1   2  boolean    gt  true

User · Answer

If your code can sensibly be written as a case statement  this is pretty decent   case mybool when TrueClass  FalseClass   puts  It s a bool   else   puts  It s something else   end

User · Answer

There is no Boolean class in Ruby  the only way to check is to do what you re doing  comparing the object against true and false or the class of the object against TrueClass and FalseClass   Can t think of why you would need this functionality though  can you explain      If you really need this functionality however  you can hack it in   module Boolean  end class TrueClass  include Boolean  end class FalseClass  include Boolean  end  true is a  Boolean     gt  true false is a  Boolean     gt  true

User · Answer

I find this to be concise and self-documenting    true  false  include  foo   If using Rails or ActiveSupport  you can even do a direct query using in   foo in   true  false    Checking against all possible values isn t something I d recommend for floats  but feasible when there are only two possible values

User · Answer

So try this out   x    true     x    false  note you need the parenthesis but this is more beautiful and compact   It even passes the suggested like  cuak  but not a  cuak     class X  def    self end end   x   X new   x    true     x    false   Note  See that this is so basic that you can use it in other languages too  that doesn t provide a  thing is boolean    Note 2  Also you can use this to say thing is one of     red    green    blue  if you add more XORS    or say this thing is one of    4  5  8  35

User · Answer

An object that is a boolean will either have a class of TrueClass or FalseClass so the following one-liner should do the trick  mybool   true mybool class    TrueClass    mybool class    FalseClass   gt  true   The following would also give you true false boolean type check result  mybool   true      TrueClass  FalseClass  include  mybool class    gt  true

User · Answer

No  Not like you have your code  There isn t any class named Boolean  Now with all the answers you have you should be able to create one and use it  You do know how to create classes don t you  I only came here because I was just wondering this idea myself  Many people might say  Why  You have to just know how Ruby uses Boolean   Which is why you got the answers you did  So thanks for the question  Food for thought  Why doesn t Ruby have a Boolean class   NameError  uninitialized constant Boolean   Keep in mind that Objects do not have types  They are classes  Objects have data  So that s why when you say data types it s a bit of a misnomer   Also try rand 2 because rand 1 seems to always give 0  rand 2 will give 1 or 0 click run a few times here  https   repl it IOPx 7  Although I wouldn t know how to go about making a Boolean class myself  I ve experimented with it but     class Boolean  lt  TrueClass   self end  true is a  Boolean      gt  false false is a  Boolean      gt  false   At least we have that class now but who knows how to get the right values

[ruby] How to check if a Ruby object is a Boolean

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