Record

Description

Concise syntax to create a reference-type with immutable properties.

• Is a shortcut for creating immutable classes
• Records are 'immutable' by default (All the record members become as 'init-only' properties).
• Records can also be partially / fully mutable - by adding mutable properties.
• Supports value-based equality.
• Supports inheritance.
• Supports non-destructive mutation using 'with' expression.
• A record CAN inherit from another record.
• A record CAN'T inherit from another class.
• A class CAN'T inherit from another record.
• A record CAN implement (inherit) one or more interfaces.
• A record CAN be 'abstract' and 'sealed'.

// Record declaration
record record_name(data_type Property1, data_type Property2, ...);

// Compiled code of Record
class record_name {
    public data_type Property1 { get; init; }
    public data_type Property2 { get; init; }

    public record_name(data_type Parameter1, data_type Parameter2)
    {
        this.Property1 = Parameter1;
        this.Property2 = Parameter2;
    }
}

Features

Mutable Properties

record record_name(data_type Property_name, ...) {
    data_type Property_name { get; set; }
}

Equality

Records provide a compiler-generated Equals() method and overloads == and != operators that compare two instances of records that compare the values of fields (but doesn't compare references).

record_name variable1 = new record_name(value1, value2);
record_name variable2 = new record_name(value1, value2);

variable1 == variable2;       // true
variable1.Equals(variable2);  // true

Inheritance

public record Parent_record_name(Properties_list);

public record Child_record_name(Properties_list) : Parent_record_name;

Example:

public record Employee(string? Name, DateTime? DateOfBirth, int? Age, double? Salary): Person(Name, DateOfBirth, Age);

Nested Record

public record Person(string Name, int Age, Address PersonAddress);

public record Address(string City);

Deconstruction

Records by default supports deconstruction

Person person1 = new Person("John", 20, new Address("London", "UK"));
var (name, _, (city, country)) = person1;

Record Struct

Record struct:

record struct record_name(Properties_list);

• A record struct is a 'struct' internally (after compilation).
• All positional parameters of a record struct are read-write properties by default.

Record or record class:

record record_name(Properties_list);

• A record is a class internally (after compilation).
• All positional parameters of a record are init-only properties by default.

Readonly record struct:

readonly record struct record_name(Properties_list);

• A readonly record struct is a 'struct' internally (after compilation).
• All positional parameters of a readonly record struct are init-only properties by default.

Record vs Record Struct

• The property of normal records are by default init only
• The property of readonly record structs are by default init only
• The property of normal record structs by default has setter and getter