Init-only setters in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Init-only setters

Create object instance

↓

Set properties with init-only setters

↓

Object is immutable after initialization

↓

Attempt to modify property after init -> Compile error

This flow shows how init-only setters allow setting properties only during object creation, making the object immutable afterward.

Execution Sample

C Sharp (C#)

public record Person
{
    public string Name { get; init; }
}

var p = new Person { Name = "Alice" };

This code creates a Person object and sets the Name property using an init-only setter during initialization.

Execution Table

Step	Action	Property Name	Value Set	Result
1	Create Person object	-	-	Object created with default values
2	Set Name during initialization	Name	"Alice"	Name property set to "Alice"
3	Attempt to modify Name after initialization	Name	"Bob"	Compile-time error: Cannot assign to 'Name' because it is init-only

💡 Execution stops because modifying init-only property after initialization causes a compile-time error.

Variable Tracker

Variable	Start	After Initialization	After Attempted Modification
p.Name	null	"Alice"	Compile error - no change

Key Moments - 2 Insights

Why can't I change the property value after the object is created?

Because the property uses an init-only setter, it can only be set during object initialization. See execution_table step 3 where modifying it later causes a compile error.

Can I set the property inside the constructor?

Yes, init-only setters allow setting properties inside the constructor or during object initialization, as shown in step 2.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of p.Name after initialization?

A "Bob"

B "Alice"

C null

D Compile error

💡 Hint

Check execution_table row 2 where Name is set during initialization.

At which step does the compile-time error occur?

A Step 3

B Step 2

C Step 1

D No error occurs

💡 Hint

See execution_table row 3 where modifying the property after initialization causes error.

If the setter was not init-only, what would happen at step 3?

A Compile-time error

B Runtime exception

C Property value changes to "Bob"

D Property remains "Alice"

💡 Hint

Without init-only, properties can be changed anytime, so step 3 would succeed.

Concept Snapshot

Init-only setters allow properties to be set only during object creation.
Syntax: public string Name { get; init; }
After initialization, properties become immutable.
Trying to set them later causes compile-time errors.
Useful for immutable data models with flexible initialization.

Full Transcript

Init-only setters in C# let you set properties only when creating an object. After the object is made, you cannot change those properties. This makes the object immutable after initialization. For example, a Person record with a Name property using init-only setter can have Name set during creation but not changed later. Trying to change it after creation causes a compile-time error. This helps keep data safe and consistent.