Basics of Ruby
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Basics of Ruby

2022, Aug 12    

Ruby Notes


  • Use Irb Prompt To Debug On Ssh Box
    • Irb Then Typing Statements Or Irb Scriptfile.Rb
  • Running File On Mac:
    • Create Xyz.Rb File - Add Shebang (#!/Usr/Bin/Env Ruby) To Specify Interpreter - Type ./Xyz.Rb To Run
  • Everything In Ruby Is An Object: Including Numbers


  • Local Var : V = 1, Global Var: $V = 1, Instance Var: @V =1, Class Var: @@V = 1
    • Also Can Turn “Hello” String To :Hello Symbol By “Hello”.To_Sym And Use It Like Print :Hello.To_S
  • Can Do Alias For Vars: Alias $A $B
  • Constants Must Being With Capital Letter: Myvar = 1 Or Myvar = 1
    • Unlike Other Langs, Consts Are Objects So Mutable, But Don’t Do That


  • (1..9) Is 1 To 9(Included)
  • (1…9) Is 1 To 9(Excluded)
  • (1..9) == 8 For Existence Check
  • (1..9).To_A: To Convert Into Array [1,2,3….9]


  • Def Methodname(P1,P2) End
  • Call: Methodname(P1,P2) Or Methodname P1 P2
  • Object Method Call: Obj.Method Or Obj#Method Or Obj::Method
  • Send Entire Function As Param: Def Funca(&Funcb): Funcb.Call(Xyz)
  • Name Ending Conventions:
    • End With ? Def Method?: Will Mostly Return Bool
    • Ends With !: Changes The Input Object
    • Ends With =: Sets Up Assignment
  • Default Arguments: Def Method(P1:”Default_Val”) Or Def Method(P1=”Default_Val”)
  • Variable No Of Arguments: Def Method(A,B,*Args): Args.Size Etc


  • Block Is A Nameless Function That Can Be Passed Around
  • Array.Each Someblock : Here Someblock Could Be { Elm Print Elm} Or Do Elm Print Elm End
  • You Can Send Block To A Function That Has Yield, The Function Will Run The Block
    • Def Myfun: Yield,
    • Call Like This: Myfun <Block> , I.E. Myfun {Puts "Something"}


  • Like Blocks But Named
  • Myproc = Proc.New {Somecode} Or Lambda {Soemcode} Or ->{Somecode} Or Proc {Somecode}
  • Calling: Myproc.Call : Executes The Code Inside Proc
  • Def Myfun(&Someproc): Yield Can Accept Proc As Function Arg Bcoz We Had & Prefix
  • Conditionals: If Test Something Elsif Something End
  • Use Begin {Code} And End{Code} To Run Something Before And After The File Code Is Run


Ruby Supports Single Inheritence

Class Myclass End
 Def Initialize(): 
   @Varname = 1
M = Myclass.New()


  • Attr :Bark, True : Sets Getter And Setter For Bark I.E. Class.Bark = X, Print Class.Bark
  • Attr_Reader :Bark : Sets Getter
  • Attr_Writter :Bark : Sets Setter
  • Attr_Accessor :Bark : Sets Getter & Setter Both

  • @Var Is Instance Variable: Unique Among Each Instance
  • @@Var Is Class Variable: Shared Across Instances
  • Static Methods: Prefix Method Definitions With Self.Methodname Or Class.Methodname To Make It Static I.E. Def Self.Run()
  • Inheritence : Class Child < Parent To Create Child Classes


  • Try Begin End
  • Catch Becomes Rescue
  • Finally Becomes Ensure
    Rescue Ioerror
    Puts "Some Error"
  • Can Also Use Raise Errortype, “Errmessage” To Throw An Error