• Ruby Notes
  • Setup
  • Basics
  • Ranges
    • Method:
    • Blocks:
    • Procs
  • Classes
    • Accessors:
  • Misc

Ruby Notes

Setup

• 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

Basics

• 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

Ranges

• (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]

Method:

• 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

Blocks:

• 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"}

    Procs

• 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

Classes

Ruby Supports Single Inheritence

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

Accessors:

• 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

Misc

• Try Begin End
• Catch Becomes Rescue
• Finally Becomes Ensure

  Begin
  Somefunction()
  Rescue Ioerror
  Puts "Some Error"
  Ensure
  Closeconnection()
  End 
  

• Can Also Use Raise Errortype, “Errmessage” To Throw An Error