Refactoring in Coding

Make changes on existing code for subsequent and constant changes of requirement.

Reference:http://www.refactoring.com/catalog/index.html

Ways of Refactorings

• Add Parameter
• Change Bidirectional Association to Unidirectional
• Change Reference to Value
• Change Unidirectional Association to Bidirectional 
• Change Value to Reference
• Collapse Hierarchy
• Consolidate Conditional Expression
• Consolidate Duplicate Conditional Fragments 
• Convert Dynamic to Static Construction
  
• Convert Static to Dynamic Construction
  
• Decompose Conditional
• Duplicate Observed Data
• Eliminate Inter-Entity Bean Communication
  
• Encapsulate Collection
• Encapsulate Downcast
• Encapsulate Field
• Extract Class
• Extract Interface
• Extract Method
• Extract Package
  
• Extract Subclass
• Extract Superclass
• Form Template Method
• Hide Delegate
• Hide Method
• Hide presentation tier-specific details from the business tier
  
• Inline Class
• Inline Method
• Inline Temp
• Introduce A Controller
  
• Introduce Assertion
• Introduce Business Delegate
  
• Introduce Explaining Variable
• Introduce Foreign Method
• Introduce Local Extension
• Introduce Null Object
• Introduce Parameter Object
• Introduce Synchronizer Token
  
• Localize Disparate Logic
  
• Merge Session Beans
  
• Move Business Logic to Session
  
• Move Class
  
• Move Field
• Move Method 
• Parameterize Method
• Preserve Whole Object
• Pull Up Constructor Body
• Pull Up Field
• Pull Up Method
• Push Down Field
• Push Down Method
• Reduce Scope of Variable
  
• Refactor Architecture by Tiers
  
• Remove Assignments to Parameters
• Remove Control Flag
• Remove Double Negative
  
• Remove Middle Man
• Remove Parameter
• Remove Setting Method
• Rename Method
• Replace Array with Object
• Replace Assignment with Initialization
  
• Replace Conditional with Polymorphism
• Replace Conditional with Visitor
  
• Replace Constructor with Factory Method 
• Replace Data Value with Object
• Replace Delegation with Inheritance
• Replace Error Code with Exception
• Replace Exception with Test
• Replace Inheritance with Delegation
• Replace Iteration with Recursion
  
• Replace Magic Number with Symbolic Constant 
• Replace Method with Method Object
• Replace Nested Conditional with Guard Clauses
• Replace Parameter with Explicit Methods
• Replace Parameter with Method
• Replace Record with Data Class
• Replace Recursion with Iteration
  
• Replace Static Variable with Parameter
  
• Replace Subclass with Fields
• Replace Temp with Query 
• Replace Type Code with Class
• Replace Type Code with State/Strategy
• Replace Type Code with Subclasses
• Reverse Conditional
  
• Self Encapsulate Field
• Separate Data Access Code
  
• Separate Query from Modifier
• Split Loop
  
• Split Temporary Variable
• Substitute Algorithm
• Use a Connection Pool
  
• Wrap entities with session
  

Summerize:
    Techniques that allow for more abstraction

• Encapsulate Field – force code to access the field with getter and setter methods
• Generalize Type – create more general types to allow for more code sharing
• Replace type-checking code with State/Strategy[6]
• Replace conditional with polymorphism [7]

Techniques for breaking code apart into more logical pieces

• Componentization breaks code down into reusable semantic units which present clear, well-defined, simple-to-use interfaces.
• Extract Class moves part of the code from an existing class into a new class.
• Extract Method, to turn part of a larger method into a new method. By breaking down code in smaller pieces, it is more easily understandable. This is also applicable to functions.

Techniques for improving names and location of code

• Move Method or Move Field – move to a more appropriate Class or source file
• Rename Method or Rename Field – changing the name into a new one that better reveals its purpose
• Pull Up – in OOP, move to a superclass
• Push Down – in OOP, move to a subclass