New Features in C# 6.0 – Primary Constructors


Update: This feature is removed from the C# 6.0 specification, probably for the next version of C#.
Primary constructors reduced declaration of various constructors with different arguments. Primary constructors is declare on the type declaration and this is why it so special. For example:


public class Person (string defaultName)
{
 private string m_Name=defaultName;
 public string Name {get;set;}
 public Person()
 {
   Name=defaultName;
 }

}

We can define Primary Constructor in combination on Auto-Property Initializer on the following way:

public class Person (string defaultName)
{
 private string m_Name=defaultName;
 public string Name {get;set;}=defaultName

}
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New Features in C# 6.0 – Auto-Property Initializers


Initialize property is repetitive task, and cannot be done in the same line as we can can done for fields. For example we can write:


public class Person
{
 private string m_Name="Default Name";
 public string Name {get;set;}
 public Person()
 {
   Name=m_Name;
 }

}

As we can see Property can be initialized only in the constructor, beside the filed which can be initialized in the same line where it is declared. The new feature in C# 6.0 defines Auto-Property initializer alowing property to be initialized like fields. The following code snippet shows the Auto-Property Initializer;


public class Person
{
 static string m_Name="Default Name";
 static string Name {get;set;}=m_Name;
}

New Features in C# 6.0 – Null-Conditional Operator


This is blog post series about new features coming in the next version of C# 6.0. The first post is about null conditional operator.

The NullReferenceException is night mare for any developer specially for developer with not much experience. Almost every created object must be check against null value before we call some of its member. For example assume we have the following code sample:

class Record
{
 public Person Person  {get;set;}
 public Activity Activity  {get;set;}
}
public static PrintReport(Record rec)
{
  string str="";
   if(rec!=null && rec.Person!=null && rec.Activity!=null)
   {
     str= string.Format("Record for {0} {1} took {2} sec.", rec.Person.FirstName??"",rec.Person.SurName??"", rec.Activity.Duration);
     Console.WriteLine(str);
   }

  return ;
}

We have to be sure that all of the object are nonnull, otherwize we get NullReferenceException.

The next version of C# provides Null-Conditional operation which reduce the code significantly.

So, in the next version of C# we can write Print method like the following without fear of NullReferenceException.


public static PrintReport(Record rec)
{
  var str= string.Format("Record for {0} {1} took {2} sec.", rec?.Person?.FirstName??"",rec?.Person?.SurName??"", rec?.Activity?.Duration);
     Console.WriteLine(str);

  return;
}

As we can see that ‘?’ is very handy way to reduce our number of if statements in the code. The Null-Conditional operation is more interesting when is used in combination of ?? null operator. For example:


 string name=records?[0].Person?.Name??"n/a";

The code listing above checks if the array of records not empty or null, then checks if the Person object is not null. At the end null operator (??) in case of null value of the Name property member of the Person object put default string “n/a”.

For this operation regularly we need to check several expressions agains null value.
Happy programming.