livefile

Overview

The livefile package provides an easy, read-write access to a live-reloadable struct instance backed by a JSON file with a transaction-like API.

Features

• Live Reload: Automatically reloads the struct instance when the underlying JSON file changes.
• Transaction-like API: Provides a safe and consistent way to update the struct instance.

Installation

To install livefile, use the following command:

go get woland.xyz/livefile

Usage

1. Define your state struct.
2. Create an instance of livefile.
3. Use the View method to read the current state.
4. Use the Update method to modify the state.
5. Use the Peek method to get a copy of the current state (a simpler version of the View method).

Example

import (
    "context"
    "fmt"

    "woland.xyz/livefile"
)

type MyState struct {
    Value int
    Name  string
}

func main() {
    ctx := context.Background()
    lf := livefile.New[MyState]("state.json")

    // View the initial state
    lf.View(ctx, func(s *MyState) {
        fmt.Println("Updated State:", *s)
    })

    // Update the state
    err := lf.Update(ctx, func(s *MyState) error {
        s.Value = 42
        s.Name = "Updated"
        return nil
    })
    if err != nil {
        panic(err)
    }

    // View the modified state
    lf.View(ctx, func(s *MyState) {
        fmt.Println("Updated State:", *s)
    })

    // Perform external modification
    if err := os.WriteFile("state.json", []byte(`{"Name":"foo","Value":100}`), 0o777); err != nil {
        panic(err)
    }

    // Get a copy of the state
    s := lf.Peek(ctx)
    fmt.Println("Final state:", s)
}