Hi !

So this one does not fit in the line “readability improvement”, however is a nice step in order to write cleaner code. Yes, I know that doesn’t make sense, let me try to explain.

Let’s start with a simple class with 2 properties. Interesting enough the property Age has a new accessor [init] to describe the property as a read-only property:

class Pet
{
  public string Name { get; set; }
  public int Age { get; init; }
}

When we create a new Pet object, we can set the initial value of Age on the construction of the object (object initialization), and that’s it. Otherwise we will get this amazing error.

Error CS8852 Init-only property or indexer 'Program.Pet.Age' can only be assigned in an object initializer, or on 'this' or 'base' in an instance constructor or an 'init' accessor. 

Until C#9, the properties in a class need to be mutable in order to support Object Initialization. And that means some extra code in the property-set definition in order to support read-only properties. Now in C# 9, this is solved with the [init] accessor 😁😁😁

I like this new one 👆 ! Not a great readability improvement, but it saves us a lot of extra code.

References

• What’s new in C# 9.0
  

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Hi !

In the line of good features, that are also nice to read, the new use of is and is not is a huge improvement in readability.

As usual, old school validation for objects and types:

// old school
if(!(testObj is MyClass)) {...}

And now, we can type the validation with some style:

// C# 9 style
if(testObj is not MyClass) {...}

I like this new one 👆, now null / not null and other validations will be the same. With an improed readability !

References

• What’s new in C# 9.0
  

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Hi !

I know I’m late to the party here, however I’m still enjoying some of the new C# 9 features a lot. I just realized that now, I can create objects in a different way, which is still super clear to read.

Disclaimer: some of the new features are cool, however my gut told me that they will make code harder to read. I also understand that I have 20 years of writing C# code in my back, so I need to find the balance here.

As usual, 2 lines of code are the best way to showcase this:

// old school
var pointOldSchool = new System.Drawing.Point(3, 5);

// new school and still very readable
System.Drawing.Point pointCSharpNine = new(3, 5);

// crappy output
Console.WriteLine("Old School: var pointOldSchool = new System.Drawing.Point(3, 5);");
Console.WriteLine(pointOldSchool);

Console.WriteLine("C#9: System.Drawing.Point pointCSharpNine = new(3, 5);");
Console.WriteLine(pointCSharpNine);

This this output as expected:

Old School: var pointOldSchool = new System.Drawing.Point(3, 5);
{X=3,Y=5}
C#9: System.Drawing.Point pointCSharpNine = new(3, 5);
{X=3,Y=5}

I like this new one 👆

References

• What’s new in C# 9.0
  

¿Con ganas de ponerte al día?

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Hi !

Our next podcast episode is focused on .Net 5. We had an amazing chat around a lot of features, and of course, C# 9 was part of the conversation.

I got this amazing post [C# 9.0: Records – Work With Immutable Data Classes] from Tomas Huber, in my reading notes and working with records is something that I wanted to test.

In a few words, a record is an immutable class. Which is super cool, because it allows some cool operations for mapping, reflection and more. Again, please read Tomas post.

On of the features of records is that once, you define a record with a constructor, there is no default constructor anymore. Let’s start with a simple person record with 3 properties for Name, Age and Married status (as boolean)

public record PersonRecord(string Name, int Age, bool Married)
{
    public override string ToString() => 
        $"Name: {Name} - Age: {Age} - Married: {Married}";
}

Losing the default constructor can be a challenge if we want to copy a record. However we can take advantage of the with expression and create new objects that uses the protected copy constructor. Let’s take a look at the same person object with a CopyUsingMarriedTrue() function that, creates a new object with the same properties changing the value of the Married property.

public record PersonRecord(string Name, int Age, bool Married = false)
{
    public Guid Id { get; init; } = Guid.NewGuid();
    public override string ToString() => 
        $"Name: {Name} - Age: {Age} - Married: {Married} - Guid: {Id}";

    public PersonRecord CopyUsingMarriedTrue() => this with { Married = true };
}

Now it’s time for a full Console test, where I create a couple of persons and check the values of the person. Important, I added a Guid Id property to test the copy and constructor behavior.

• Lines 14 to 18, I created a Bruno person with Married as True, and I created a BrunoMarried to check the new created object.
• Lines 20 to 25, I created a Valentino person with Married as False and I created a ValentinoMarried to check the new created object.

The output is an awesome surprise. I mean, my code always surprise me, however using this feature is an awesome surprise !

start
Name: Bruno - Age: 40 - Married: True - Guid: 82e60022-0fb2-456d-89c0-ab88bef5aff6
Bruno Is Married created
Name: Bruno - Age: 40 - Married: True - Guid: 82e60022-0fb2-456d-89c0-ab88bef5aff6
-----------------------------------
Name: Valentino - Age: 13 - Married: False - Guid: 7acca9e2-f461-4fc9-8e29-06f6f0ffb6c6
Valentino Is Married created
Name: Valentino - Age: 13 - Married: True - Guid: 7acca9e2-f461-4fc9-8e29-06f6f0ffb6c6

References

• C# 9.0: Records – Work With Immutable Data Classes
• Microsoft Docs, Create record types

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