Refactor C# code to become more expressive

Introduction 

This article brings clarification on some small tips to keep your code elegant and clean.

Background 

Recently i began as architect on a large e-commerce corporation. My mission is to optimize code, by using cutting edge technologies, code reviewing and code rewriting/refactoring.

The main purpose of this article is to present some techniques on how to rewrite code in elegant way. 

Using the code 

Refactoring and make use of coalesce:  

/*  Coalesce: */
if (Request["search"] == string.Empty || Request["search"] == null)
    base.searchText = string.Empty; 
else 
    base.searchText = Convert.ToString(Request["search"]);
return base.searchText;
/*  Can be written as:  */
base.searchText = Request["search"] ?? String.Empty; 

Inversion of condition (AKA early return):

/*Inversion of condition:*/
public void DoSomething(String url)
{
    if (!string.IsNullOrEmpty(url))
    {
        if (migrate)
        {
            // code here
        }
    }
    else
    {
        PopulatePage(); 
    }
}
/*  Can be written as:   */
public void DoSomething(String url)
{
    if(String.IsNullOrEmpty(url))
    {
	PopulatePage();
	return;
    }        
    if (domainMigration)
    {
        // code here
    }        
}

Avoiding double calls:

/*  Double calls:   */

if (string.IsNullOrEmpty(Request["location"]))
    url = (FacadeFactory.GetCatalog()).ValidateUrl(filter.Value, canonicalUrl);
else
    url = (FacadeFactory.GetCatalog()).ValidateUrlByName(Request["location"], canonicalUrl);

/*  Can be written as:  */
var catalog = FacadeFactory.GetCatalog();
if (string.IsNullOrEmpty(Request["location"]))
    url = catalog.ValidateUrl(filter.Value, canonicalUrl);
else
    url = catalog.ValidateUrlByName(Request["location"], canonicalUrl);

/*  or */
var catalog = FacadeFactory.GetCatalog();
url = if (string.IsNullOrEmpty(Request["location"]))
    ? catalog.ValidateUrl(filter.Value, canonicalUrl)
    : catalog.ValidateUrlByName(Request["location"], canonicalUrl);

Comparison simplification

/*  compare using Contains  */
if (store.Current == Stores.Starbucks
    || store.Current == Stores.BarnsAndNobles
    || store.Current == Stores.Amazon)
{
    //do something
}

/*  can be written as:  */
var stores = new[]{ Stores.Starbucks, Stores.BarnsAndNobles, Stores.Amazon };
if (stores.Contains(store.Current))
{
    //do something
}

Defensive programming against null objects:

/*  defensive programming   */
var categories = Platform.ECommerce.Services.GetCategories();

var location = Helper.StringHelper.RemoveSpecialChars(
                    categories.Where(a => a.LocationId == filter).FirstOrDefault().Name);
//line above: possible NullReferenceException

var someString = ConfigurationManager.AppSettings["urlSite"] + "/" + location + "/?" + Request.QueryString.ToString();

/* can be written as:   */

var categories = Platform.ECommerce.Services.GetCategories();

var location = Helper.StringHelper.RemoveSpecialChars(
    categories.Where(a => a.LocationId == filter.Select(c=>c.Name).FirstOrDefault() ?? String.Empty));
//safe property access

Points of Interest 

By using small tips and techniques, the code readability gets enhanced and the maintenance makes less painful. Some parts of this code can be refactored (using filters, extension methods, etc), but in this case i need to make greater changes that impacts the system. 

History 

Jun, 21, 2012:
 - Coalesce tips;
 - Avoiding double calls
 - Optimizing comparison
 - Defensive programming against null objects