feat(factory): add createApp()

[yusukebe]

This PR introduces createApp() in hono/factory as an experimental feature. If you use this method with createFactory(), you can avoid redundancy in the definition of Env types.

Before:

const app = new Hono<Env>()

const mw = createMiddleware<Env>(async(c, next) => {
  await next()
})

With this PR:

const factory = createFactory<Env>()

const app = factory.createApp()

const mw = factory.createMiddleware(async (c, next) => {
  await next()
})

Using the "Simple Factory" pattern with the Factory helper, there is no need to write type definitions in global.d.ts with possible type conflicts. Also, you don't have to have Env definitions in multiple places.

// factory-with-db.ts
type Env = {
  Bindings: {
    MY_DB: D1Database
  }
  Variables: {
    db: DrizzleD1Database
  }
}

export default createFactory<Env>({
  initApp: (app) => {
    app.use(async (c, next) => {
      const db = drizzle(c.env.MY_DB)
      c.set('db', db)
      await next()
    })
  },
})

// crud.ts
import factoryWithDB from './factory-with-db'

const app = factoryWithDB.createApp()

app.post('/posts', (c) => {
  c.var.db.insert
})

In the future, I recommend the use of this "Simple Factory" pattern for larger applications, such as those using HonoX.

Author should do the followings, if applicable

• Add tests
• Run tests
• yarn denoify to generate files for Deno

[yusukebe]

Hi, @usualoma What do you think of this? I'd like to recommend the Factory pattern.

[usualoma]

@yusukebe 👍 We will be able to define an app concisely!

[yusukebe]

@usualoma

Thanks!