The following are the new features that introduce in C# 12. Check out the new C# 12 preview features!
1. Default value for Lambda Expressions (Optional
parameters in Lambda Expressions)
2. Primary Constructors
3. Alias any type
4. Interceptors
In C# 12, you can provide default
values for parameters on lambda expressions.
For example,
var IncrementValueBy = (int a, int b = 1) => a + b;
Console.WriteLine(IncrementValueBy(1)); // 2
Console.WriteLine(IncrementValueBy
(1, 2)); // 3
2) Primary Constructors:
Primary constructor parameters are in
scope for the entire body of the class.
In the Primary constructors, you can
now create primary constructors in any class and struct.
In the Primary constructors, you are
no longer restricted to record types.
For example,
Let's start to create Primary
Constructors with a User class.
Here's how you would define a User
class using a Primary Constructor,
public class User(string
name, int age)
{
public string Name { get; init; } =
name;
public int Age { get; init; } =
age;
}
In the above User class, we
have defined two properties: Name, and Age. Also, we have used
the init keyword to make the properties read-only and initialized them
directly within the ‘Primary Constructors’ parameter list.
Here is how to would create a new User
object using the Primary Constructor i.e.
var
user = new User("Anil
Singh",
35);
The User object is created with
Name and Age which are used to initialize the corresponding
properties.
Noted Point: The class 'User' doesn't
have a constructor method with a parameter-less constructor. It will get a
compiler error if we try to create an object using the default constructor.
Example 2,
All bank accounts have properties for
the account number and an owner.
The following code initializes two
properties in the primary constructor parameters:
public class BankAccount(string
accountID, string owner)
{
public string AccountID { get; } =
accountID;
public string Owner { get; } = owner;
public override string ToString() => $"Account ID: {AccountID}, Owner: {Owner}";
}
For example, the BankAccount class
has specific requirements for the owner and accountID parameters: The owner
must not be null or whitespace, and the accountID must be a string containing
10 digits. You can add this validation when you assign the corresponding
properties:
public class BankAccount(string
accountID, string owner)
{
public string AccountID { get; } =
ValidAccountNumber(accountID) ? accountID : throw new ArgumentException("Invalid account number", nameof(accountID));
public string Owner { get; } = string.IsNullOrWhiteSpace(owner)
? throw new
ArgumentException("Owner
name cannot be empty or null", nameof(owner)) : owner;
public override string ToString() => $"Account ID: {AccountID}, Owner: {Owner}";
public static bool ValidAccountNumber(string accountID) => accountID?.Length == 10 &&
accountID.All(c => char.IsDigit(c));
}
In the above example, we can see how
we can validate the constructor parameters before assigning them to the
properties. Also, we can use built-in methods, like
String.IsNullOrWhiteSpace(String), or your own validation method, just like the above ValidAccountNumber method.
3) Alias any
type:
Now, we can use the using alias
directive to alias any type, not just named types. That means we can create
semantic aliases for tuple types, array types, pointer types, or other unsafe
types.
For example, we can define an alias
for the tuple as given below,
using point3D = (int x, int y, int z);
public void AliasAnyType()
{
point3D point3D = (2, 4, 6);
Console.WriteLine($"{point3D.x},{point3D.y},{point3D.z}"); //2,4,6
}
In addition to this overview, you can also find detailed documentation in the What’s New in C# 12 article on Microsoft.
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Anil Singh is an author, tech blogger, and software programmer. Book writing, tech blogging is something do extra and Anil love doing it. For more detail, kindly refer to this link..
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