@stamp/configure

@stamp/configure

Access configuration of your stamps anywhere

Configuration is powerful feature of stamps as it allows you to store additional information with the stamp without interfering with properties or methods. Consider following example.

Usage

import compose from '@stamp/compose'
import jwt from 'jsonwebtoken'

const Jwt = compose({
  configuration: {
    jwtSecret: process.env.SECRET,
  },
  initializers: [
    initializeJwt(_, { stamp }) {
      const { jwtSecret } = stamp.compose.configuration
      ...
      this.createJwtToken = (payload) => jwt.sign(payload, jwtSecret)
      this.verifyJwtToken = (token) => jwt.verify(token, jwtSecret)
    }
  ]
})

That approach brings several advantages.

• Clearly specify what makes the stamp tick.
• Configured values are immutable.
• Stamp with a modified configuration can be made.

The last bullet is especially useful for automated testing allowing you to insert different values based on various conditions. Unfortunately, there is apparent boilerplate hidden behind this, and it can get tedious for a larger project.

Now consider next example that is using @stamp/configure stamp.

import Configure from '@stamp/configure'
import jwt from 'jsonwebtoken'

const Jwt = Configure.compose({
  configuration: {
    jwtSecret: process.env.SECRET,
  },
  methods: {
    createJwtToken(payload) {
      return jwt.sign(payload, this.config.jwtSecret)
    },
    verifyJwtToken(token) {
      return jwt.verify(token, this.config.jwtSecret)
    }
  }
})

Looks good, doesn't it? But wait, all those advantages of the configuration are suddenly gone, right? Not exactly.

Under the hood, we are using @stamp/privatize stamp. That allows us to access this.config within our methods and yet keep them hidden from outside world. Immutability is ensured by using Object.freeze().

The deepConfiguration gets assigned to the same this.config object as well while the configuration has a precedence over it. In case of name conflict, the value from configuration always wins.

No fan of @stamp/privatize ?

By including @stamp/configure your whole stamp is privatized by default which you may not like that much. For that case, we are offering opt-out option of using Configure.noPrivatize() instead of plain Configure.