IDerivedAttributeDescriptor abstract#

Represents a derived attribute whose value is inferred rather than stored.

Derived attributes do not persist values in memory or databases because their values are logically implied by the inheritance hierarchy and can be calculated or determined from other attribute relationships.

This type of attribute is commonly used in schema modeling to represent computed properties, inherited characteristics, or relationships that can be dynamically resolved rather than explicitly stored.

Constructors#

IDerivedAttributeDescriptor()#

Properties#

attributeName no setter inherited#

The name of the attribute as defined in the schema.

Inherited from IAttributeDescriptor.

String get attributeName;

attributeOwner no setter inherited#

The type ID of the ENTITY that owns (declares) this attribute.

Inherited from IAttributeDescriptor.

int get attributeOwner;

attributeTypeId no setter inherited#

The core type ID of the attribute.

This can be an instance type ID, a SELECT type ID, an ENUM type ID, or a simple type ID (e.g., for INTEGER, STRING).

Inherited from IAttributeDescriptor.

int get attributeTypeId;

baseType no setter inherited#

For aggregate attributes (e.g., LIST OF X), this is the type ID of the base element X.

Returns 0 if the attribute is not an aggregate.

Inherited from IAttributeDescriptor.

int get baseType;

derivedIndex no setter inherited#

The attribute index of the derived attribute in its parent type.

Inherited from IAttributeDescriptor.

int get derivedIndex;

derivedType no setter inherited#

The type ID that was derived from this attribute, if it is a derived attribute.

Returns 0 if this is not a derived attribute.

Inherited from IAttributeDescriptor.

int get derivedType;

derivingType no setter inherited#

The type ID this attribute is derived from, if it is a deriving attribute.

Returns 0 if this is not a deriving attribute.

Inherited from IAttributeDescriptor.

int get derivingType;

flag no setter inherited#

Supplemental flags defining the attribute's properties.

The relevant values are:

• PIAttributeFlag.NORMAL
• PIAttributeFlag.OPTIONAL
• PIAttributeFlag.DERIVED

Inherited from IAttributeDescriptor.

PIAttributeFlag get flag;

fundamentalType no setter inherited#

The fundamental categorization of the attribute's data type.

Inherited from IAttributeDescriptor.

FundamentalType get fundamentalType;

hashCode no setter inherited#

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

external int get hashCode;

isAggregate no setter inherited#

Whether this attribute is an aggregate (e.g., LIST, SET, ARRAY).

Inherited from IAttributeDescriptor.

bool get isAggregate;

isContainerType no setter inherited#

Whether this attribute's type is a complex container type.

See also: ComplexFunTypes.

Inherited from IAttributeDescriptor.

bool get isContainerType;

isDerived no setter inherited#

Whether this is a derived attribute.

A helper property for the case where flag == PIAttributeFlag.DERIVED.

Inherited from IAttributeDescriptor.

bool get isDerived;

isInstanceType no setter inherited#

Whether this attribute's type is an instance type (e.g., an ENTITY).

Inherited from IAttributeDescriptor.

bool get isInstanceType;

isNull no setter inherited#

Indicates whether the object represents a null value.

Returns true if the object is considered null according to its implementation, false otherwise.

Inherited from INullableObject.

bool get isNull;

runtimeType no setter inherited#

A representation of the runtime type of the object.

Inherited from Object.

external Type get runtimeType;

Methods#

isEquivalent() inherited#

Inherited from IAttributeDescriptor.

bool isEquivalent(IAttributeDescriptor other);

noSuchMethod() inherited#

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

toString() inherited#

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

external String toString();

Operators#

operator ==() inherited#

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

external bool operator ==(Object other);