Saturday, 20 September 2008

Refactoring Techniques - High Performance Code


This blog will hold the collection of refactoring and performance techniques.

What is Refactoring?

Refactoring is a process to improve upon the design of existing code, while preserving its intended functionality.



Bad Code Smells:
Refactoring Techniques:
Here, you can find an excellent list of refactoring techniques with examples. In below, I am going to duplicate some:

1)

Example:
List items = new List();

Bad: items.Count
Good: items.Length

Reason:
Length property is faster than Count performance-wise.

2)

Example:

Bad:
int[] items = new int[2];

Good:
List items = new List();

Reasons:
1. Using Generic list gives you more power and control over the list
2. You do not have to specify the length of the array at the time of its creation

3) Extract Constant

Bad:
public static double CalcCircumference(double diameter)
{ return 3.14 * diameter; }

Good:
public const double PI = 3.14;
public static double CalcCircumference (double diameter)
{ return PI * diameter; }

Reasons:
1. If we need to change PI value, we only need to change it in one place
2. Increased readibility

4) Extract Method
http://www.xtreme-simplicity.net/ExtractMethod.htm

5) Decompose IF Conditional
http://www.xtreme-simplicity.net/DecomposeConditiona.htm

6) Extract Variable
http://www.xtreme-simplicity.net/ExtractVariable.htm

7) Encapsulate Field:
http://msdn.microsoft.com/en-us/library/ms379618.aspx

8) Extract Interface:
http://msdn.microsoft.com/en-us/library/ms379618.aspx

9) Reorder Method Parameters
http://msdn.microsoft.com/en-us/library/ms379618.aspx

10) Rename (type, method, class, namespace, variable)
http://msdn.microsoft.com/en-us/library/ms379618.aspx

11) Promote Local Variable to Parameter
http://msdn.microsoft.com/en-us/library/ms379618.aspx

Reasons:
1) To inject dependency (object, type, etc)

12) Use StringBuilder instead of String

For another list of refactoring techniques, please see http://www.refactoring.com/catalog/index.html


Refactoring Tools:

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