store

Store Package

Reactive state management for Galaxy Go/WASM applications, inspired by Astro's nano stores.

Features

• Type-safe reactive stores using Go generics
• Three store types: Atom, Map, Computed
• HMR integration - state persists across hot reloads
• Subscription-based reactivity
• Thread-safe with mutex protection
• Zero dependencies - uses only stdlib and syscall/js

Quick Start

import "github.com/withgalaxy/galaxy/pkg/store"

count := store.NewAtom(0)
doubled := store.NewComputed(count, func(v int) int { return v * 2 })

count.Subscribe(func(val int) {
    fmt.Println("Count:", val)
})

count.Set(5) // Prints: Count: 5

Store Types

Atom[T]

Single value container with type safety.

stringStore := store.NewAtom("hello")
intStore := store.NewAtom(42)
structStore := store.NewAtom(User{Name: "Alice"})

MapStore

Key-value container for structured data.

user := store.NewMap(map[string]any{
    "name": "Alice",
    "age": 30,
})
user.SetKey("age", 31)

Computed[T]

Derived values from other stores.

doubled := store.NewComputed(count, func(v int) int {
    return v * 2
})

HMR Support

Enable HMR to preserve state across hot reloads:

count := store.NewAtomWithHMR(0, "my-counter")
user := store.NewMapWithHMR(initialData, "user-state")

API

Atom[T]

• NewAtom[T](initial T) *Atom[T]
• NewAtomWithHMR[T](initial T, key string) *Atom[T]
• Get() T
• Set(value T)
• Update(fn func(T) T)
• Subscribe(callback func(T)) Unsubscriber
• Value() T - alias for Get()

MapStore

• NewMap(initial map[string]any) *MapStore
• NewMapWithHMR(initial map[string]any, key string) *MapStore
• Get() map[string]any
• GetKey(key string) any
• Set(value map[string]any)
• SetKey(key string, value any)
• DeleteKey(key string)
• Subscribe(callback func(map[string]any)) Unsubscriber

Computed[T]

• NewComputed[S, T](source ReadableStore[S], fn func(S) T) *Computed[T]
• Get() T
• Subscribe(callback func(T)) Unsubscriber
• Destroy() - cleanup source subscription

Examples

See galaxy/examples/basic/src/pages/:

• store-counter.gxc - Basic usage
• store-todos.gxc - Todo app with complex state

Documentation

Full documentation: galaxy-docs/src/content/docs/stores-guide.md

Testing

Tests are in store_test.go with WASM build tags. Cannot run directly without browser environment.

Future Extensions

Designed for multi-language support via ReadableStore interface abstraction.