Struct DynamicSubscriptions 

pub struct DynamicSubscriptions<U> { /* private fields */ }

A container for managing multiple subscriptions with ID-based tracking.

This struct provides a common abstraction for scenarios that need to:

• Store multiple subscriptions/items dynamically
• Add new items and get a unique ID
• Remove specific items by ID (e.g., when an inner observable completes)
• Unsubscribe all items at once

Design

• SmallVec Optimization: Uses SmallVec<[_; 2]> to avoid heap allocation for the common case of 0-2 items.
• Pre-allocation Pattern: Supports reserve_id() + insert() to handle cyclic dependencies where the ID is needed before the item exists.

Examples

use rxrust::subscription::DynamicSubscriptions;

let mut subs: DynamicSubscriptions<()> = DynamicSubscriptions::default();

// Normal add pattern
let id1 = subs.add(());
assert_eq!(subs.len(), 1);

// Pre-allocation pattern (for cyclic dependencies)
let id2 = subs.reserve_id();
// ... create observer with id2 ...
// ... subscribe and get subscription ...
subs.insert(id2, ());
assert_eq!(subs.len(), 2);

// Remove by ID
assert!(subs.remove(id1).is_some());
assert_eq!(subs.len(), 1);

Implementations

impl<U> DynamicSubscriptions<U>

pub fn new() -> Self

Create an empty container.

pub fn add(&mut self, item: U) -> usize

Add an item and return its unique ID.

pub fn reserve_id(&mut self) -> usize

Reserve the next ID without adding an item.

Use this with insert() when you need the ID before the item exists (e.g., for cyclic dependencies in observer patterns).

pub fn insert(&mut self, id: usize, item: U)

Insert an item with a pre-reserved ID.

The ID should have been obtained from reserve_id().

pub fn remove(&mut self, id: usize) -> Option<U>

Remove an item by ID. Returns true if found and removed.

pub fn contains(&self, id: usize) -> bool

Check if an ID exists in the container.

pub fn len(&self) -> usize

Get the number of items.

pub fn is_empty(&self) -> bool

Check if empty.

pub fn drain(&mut self) -> impl Iterator<Item = U> + '_

Drain all items.

pub fn iter(&self) -> impl Iterator<Item = &U>

Iterate over all items.

pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut U>

Iterate over all items mutably.

impl<U: Subscription> DynamicSubscriptions<U>

pub fn unsubscribe_all(&mut self)

Unsubscribe all items and clear the container.

pub fn all_closed(&self) -> bool

Check if all items are closed.

Trait Implementations

impl<U> Default for DynamicSubscriptions<U>

fn default() -> Self

Returns the “default value” for a type.