StdLib Disposable WeakRef

DisposableStack, FinalizationRegistry, and WeakRef

Resource management and weak reference utilities.

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DisposableStack

Manages a stack of disposable resources for the using declaration.

Implementation Status: 100% Complete (marked FLAKY)

using stack = new DisposableStack();
stack.use(resource);  // Auto-disposed when block exits

Constructor

Method	Status	Description
new DisposableStack()	Implemented	Creates empty stack

Prototype Methods

Method	Status	Description
use(value)	Implemented	Adds disposable, returns value
adopt(value, onDispose)	Implemented	Adds value with custom dispose
defer(onDispose)	Implemented	Adds cleanup callback
move()	Implemented	Transfers resources to new stack
dispose()	Implemented	Disposes all resources
[Symbol.dispose]()	Implemented	Alias for dispose()
disposed (getter)	Implemented	Is stack disposed

Example

{
    using stack = new DisposableStack();
    const file = stack.use(openFile("data.txt"));
    stack.defer(() => console.log("cleanup"));
    // file disposed, "cleanup" logged when block exits
}

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AsyncDisposableStack

Async version of DisposableStack for await using.

Implementation Status: 100% Complete (marked FLAKY)

await using stack = new AsyncDisposableStack();
stack.use(asyncResource);

Constructor

Method	Status	Description
new AsyncDisposableStack()	Implemented	Creates empty stack

Prototype Methods

Method	Status	Description
use(value)	Implemented	Adds async disposable
adopt(value, onDispose)	Implemented	Adds with custom async dispose
defer(onDispose)	Implemented	Adds async cleanup callback
move()	Implemented	Transfers to new stack
disposeAsync()	Implemented	Async dispose all resources
[Symbol.asyncDispose]()	Implemented	Alias for disposeAsync()
disposed (getter)	Implemented	Is stack disposed

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FinalizationRegistry

Allows cleanup callbacks when objects are garbage collected.

Implementation Status: 0% (Stubs Only)

Constructor

Method	Status	Description
new FinalizationRegistry(callback)	Stub	Creates stub instance

Prototype Methods

Method	Status	Description
register(target, heldValue, token)	Not Implemented	Throws NotImplementedException
unregister(token)	Not Implemented	Throws NotImplementedException
cleanupSome(callback)	Missing	Not defined

Note: FinalizationRegistry requires integration with the .NET garbage collector which is not implemented.

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WeakRef

Holds a weak reference to an object.

Implementation Status: Simplified (Not True Weak)

Constructor

Method	Status	Description
new WeakRef(target)	Implemented	Creates "weak" reference

Prototype Methods

Method	Status	Description
deref()	Implemented	Returns target or undefined

Important Limitation

The current implementation stores the target as a regular property, not a true weak reference:

// Current implementation (simplified)
instance.SetProperty("_target", target);  // Strong reference!

This means:

• Objects held by WeakRef will never be garbage collected
• deref() will never return undefined due to GC
• WeakRef behaves like a regular object wrapper

For true weak reference semantics, use WeakMap/WeakSet which use ConditionalWeakTable.

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Disposal Protocol

Symbol.dispose

Sync disposal uses [Symbol.dispose]:

const resource = {
    [Symbol.dispose]() {
        console.log("disposed");
    }
};

{
    using r = resource;
}  // "disposed" logged

Symbol.asyncDispose

Async disposal uses [Symbol.asyncDispose]:

const asyncResource = {
    async [Symbol.asyncDispose]() {
        await cleanup();
        console.log("async disposed");
    }
};

{
    await using r = asyncResource;
}  // "async disposed" logged

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Files

File	Purpose
StdLib/DisposableStack/DisposableStackConstructor.cs	Constructor
StdLib/DisposableStack/DisposableStackPrototype.cs	Prototype methods
StdLib/AsyncDisposableStack/AsyncDisposableStackConstructor.cs	Async constructor
StdLib/AsyncDisposableStack/AsyncDisposableStackPrototype.cs	Async methods
StdLib/FinalizationRegistry/FinalizationRegistryConstructor.cs	Stub
StdLib/FinalizationRegistry/FinalizationRegistryPrototype.cs	Stubs
StdLib/WeakRef/WeakRefConstructor.cs	Constructor
StdLib/WeakRef/WeakRefPrototype.cs	deref()
JsTypes/JsDisposableStackBase.cs	Shared base class

See Also

• WeakCollections - WeakMap/WeakSet (true weak references)
• Symbol-System - Symbol.dispose and Symbol.asyncDispose