Assignable<T> Record

Generic record that wraps a value of type T and tracks whether it has been explicitly assigned.

Remarks

Assignable<T> is similar to Nullable<T> but is designed to track assignment state rather than null state. This is useful in scenarios where you need to distinguish between a value that was never set and one that was explicitly assigned, such as partial updates in ORM operations or REST API patch requests. An unassigned instance has IsAssigned set to False. Accessing the Value property of an unassigned instance raises EUnassignedConvertException. Use ValueOrDefault to safely retrieve the value without raising an exception. Implicit operators allow seamless conversion between T and Assignable<T>.

Syntax

Unit: Bcl.Types.Assignable

Assignable<T> = record;

Constructors

Name	Description
Create	Creates a new Assignable<T> instance with the specified value, marking it as assigned.

Operators

Name	Description
Equality	Adapts the = operator so it returns true when both instances have the same values.
Inequality	Adapts the <> operator so it returns true when both instances have different values.

Properties

Name	Description
IsAssigned	Indicates whether a value has been explicitly assigned to this instance.
Value	Gets or sets the wrapped value.
ValueOrDefault	Gets the wrapped value if assigned, or the default value for type T if not assigned.
Empty	Returns a new unassigned Assignable<T> instance.