Code Refactoring Part 1

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What is Code Refactoring?

Code Refactoring is the process of restricting existing code. Refactoring increase non-functional attributes of software application. It is a process of taking existing code and improves it while it makes code more readable, understandable, and clean.

"Refactoring is the process of changing a software system in such a way that it does not alter the external behavior of the code yet improves its internal structure." – Martin Fowler

Before refactoring we need to identify “Code Smells” in code. Refactoring will be based on “Code Smells”. Refactoring also removes “Code Smells” from your project, this is done to get certain benefits and these benefits may not be consumable immediately but over the long term. Refactoring can be different types like

Code Refactoring
Database Refactoring
User Interface Refactoring

Now I will discuss about code refactoring.

Why Code Refactoring?

To improve the design of Software application
Easy to extend new requirements in the application.
To Make Software easy to understand.
To Make program run faster.
To Make Re-Usable Components.
To find Bug and Easy to Fix.
To Make application component are loosely couple

Output after Refactoring

Makes code more readable.
Cleanup code and makes it tidier.
Removes redundant, unused code and comments.
Improves performance.
Makes some things more generic.
Keeps code DRY ( Don’t Repeat Yourself)
Combines and dispose “Like” or “Similar” code.
Splitting out long functions into more manageable bite.
Create re-usable code.
Better class and function cohesion.

Agile practices come along with refactoring and code smells for identifying refactoring needs. In computer programming, code smell is any symptom in the source code of a program that possibly indicates a deeper problem. Code smells are usually not bugs—they are not technically incorrect and do not currently prevent the program from functioning. Instead, they indicate weaknesses in design that may be slowing down development or increasing the risk of bugs or failures in the future.

Common Code Smells and their refactoring

Long Method
Lazy Class
Dead Code
Refused Bequest
Inappropriate naming
Comments
Duplicated code
Primitive obsession
Large class
God class
Middle man
Data clumps
Data class
Long parameter list
Switch statements
Speculative generality
Oddball solution
Feature envy
Black sheep
Contrived complexity
Divergent change
Shotgun Surgery

Long Method Treatments

Reduce the method body, use extract method.
Replace temp with query
Introduce parameter object
Preserve Whole Object
Replace Method with Method Object
Decompose Conditional

Extract Method Example

Bad Code

void PrintOwning(double amount){
    PrintBanner();
    / / print details
    System.Console.Out.WriteLine(“name: “+ name);
    System.Console.Out.WriteLine(“amount: “+ amount);
}

After Refactoring:

void PrintOwning(double amount){
    PrintBanner();
    PrintDetails(amount);
}
void PrintDetails(double amount){
   System.Console.Out.WriteLine(“name: “+ name);
   System.Console.Out.WriteLine(“amount: “+ amount);
}

Replace Temp with Query Example

Bad Code

double basePrice  = _quanity  *  _itemPrice;
if(basePrice  >  1000) {
    return basePrice * 0.95;
 }  else {
    return basePrice * 0.98;
}

After Refactoring:

if(getBasePrice()  >  1000) {
    return getBasePrice()  * 0.95;
}  else {
    return getBasePrice() * 0.98;
}
double getBasePrice() {
    return _quanitiy * _itemPrice;
}

Introduce Parameter Object Example

Replace Method with Method Object Example

Bad Code

//class Order....
double price() {
    double primaryBasePrice;
    double secoundaryBasePrice;
    double tertiaryBasePrice
 // long computation;
 .....
}