MirrorSystem abstract

abstract class MirrorSystem

A MirrorSystem is the main interface used to reflect on a set of associated libraries.

At runtime each running isolate has a distinct MirrorSystem.

It is also possible to have a MirrorSystem which represents a set of libraries which are not running -- perhaps at compile-time. In this case, all available reflective functionality would be supported, but runtime functionality (such as invoking a function or inspecting the contents of a variable) would fail dynamically.

Constructors

MirrorSystem()

MirrorSystem()

Properties

dynamicType no setter

TypeMirror get dynamicType

A mirror on the dynamic type.

Implementation

TypeMirror get dynamicType;

hashCode no setter inherited

int get hashCode

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.

Implementation

external int get hashCode;

isolate no setter

IsolateMirror get isolate

A mirror on the isolate associated with this MirrorSystem.

This may be null if this mirror system is not running.

Implementation

IsolateMirror get isolate;

libraries no setter

Map<Uri, LibraryMirror> get libraries

All libraries known to the mirror system, indexed by their URI.

Returns an unmodifiable map of the libraries with LibraryMirror.uri as keys.

For a runtime mirror system, only libraries which are currently loaded are included, and repeated calls of this method may return different maps as libraries are loaded.

Implementation

Map<Uri, LibraryMirror> get libraries;

neverType no setter

TypeMirror get neverType

A mirror on the Never type.

Implementation

TypeMirror get neverType;

runtimeType no setter inherited

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

voidType no setter

TypeMirror get voidType

A mirror on the void type.

Implementation

TypeMirror get voidType;

Methods

findLibrary()

LibraryMirror findLibrary(Symbol libraryName)

Returns the unique library named libraryName if it exists.

If no unique library exists, an error is thrown.

Implementation

external LibraryMirror findLibrary(Symbol libraryName);

noSuchMethod() inherited

dynamic noSuchMethod(Invocation invocation)

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.

Implementation

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

toString() inherited

String toString()

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.

Implementation

external String toString();

Operators

operator ==() inherited

bool operator ==(Object other)

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.

Implementation

external bool operator ==(Object other);

Static Methods

getName()

String getName(Symbol symbol)

Returns the name of symbol.

Implementation

external static String getName(Symbol symbol);

getSymbol()

Symbol getSymbol(String name, [LibraryMirror? library])

Returns a symbol for name.

If library is not a LibraryMirror or if name is a private identifier and library is null, throws an ArgumentError. If name is a private identifier, the symbol returned is with respect to library.

The following text is non-normative:

Using this method may result in larger output. If possible, use the const constructor of Symbol or symbol literals.

Implementation

external static Symbol getSymbol(String name, [LibraryMirror? library]);