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# figgy-pudding [](https://npm.im/figgy-pudding) [](https://npm.im/figgy-pudding) [](https://travis-ci.org/zkat/figgy-pudding) [](https://ci.appveyor.com/project/zkat/figgy-pudding) [](https://coveralls.io/github/zkat/figgy-pudding?branch=latest)
# Death to the God Object! Now Bring Us Some Figgy Pudding!
[`figgy-pudding`](https://github.com/zkat/figgy-pudding) is a simple JavaScript library for managing and composing cascading options objects -- hiding what needs to be hidden from each layer, without having to do a lot of manual munging and passing of options.
## Install
`$ npm install figgy-pudding`
## Table of Contents
* [Example](#example)
* [Features](#features)
* [API](#api)
* [`figgyPudding(spec)`](#figgy-pudding)
* [`Opts(values)`](#opts)
* [`opts.get()`](#opts-get)
* [`opts.concat()`](#opts-concat)
### Example
```javascript
const puddin = require('figgyPudding')
const RequestOpts = puddin({
follow: {
default: true
},
streaming: {
default: false
},
log: {
default: require('npmlog')
}
})
const MyAppOpts = puddin({
log: {
default: require('npmlog')
},
cache: {
default: './cache'
}
})
function start (opts) {
opts = MyAppOpts(opts)
initCache(opts.get('cache'))
opts.get('streaming') // => undefined
reqStuff('https://npm.im/figgy-pudding', opts)
}
function reqStuff (uri, opts) {
opts = RequestOpts(opts)
require('request').get(uri, opts) // can't see `cache`
}
```
### Features
* Hide options from layer that didn't ask for it
* Shared multi-layer options
### API
#### <a name="figgy-pudding"></a> `> figgyPudding({ key: { default: val } | String }, [opts])`
Defines an Options constructor that can be used to collect only the needed
options.
An optional `default` property for specs can be used to specify default values
if nothing was passed in.
If the value for a spec is a string, it will be treated as an alias to that
other key.
##### Example
```javascript
const MyAppOpts = figgyPudding({
lg: 'log',
log: {
default: () => require('npmlog')
},
cache: {}
})
```
#### <a name="opts"></a> `> Opts(...providers)`
Instantiates an options object defined by `figgyPudding()`, which uses
`providers`, in order, to find requested properties.
Each provider can be either a plain object, a `Map`-like object (that is, one
with a `.get()` method) or another figgyPudding `Opts` object.
When nesting `Opts` objects, their properties will not become available to the
new object, but any further nested `Opts` that reference that property _will_ be
able to read from their grandparent, as long as they define that key. Default
values for nested `Opts` parents will be used, if found.
##### Example
```javascript
const ReqOpts = figgyPudding({
follow: {}
})
const opts = ReqOpts({
follow: true,
log: require('npmlog')
})
opts.get('follow') // => true
opts.get('log') // => Error: ReqOpts does not define `log`
const MoreOpts = figgyPudding({
log: {}
})
MoreOpts(opts).get('log') // => npmlog object (passed in from original plain obj)
MoreOpts(opts).get('follow') // => Error: MoreOpts does not define `follow`
```
#### <a name="opts-get"></a> `> opts.get(key)`
Gets a value from the options object.
##### Example
```js
const opts = MyOpts(config)
opts.get('foo') // value of `foo`
```
#### <a name="opts-concat"></a> `> opts.concat(...moreProviders)`
Creates a new opts object of the same type as `opts` with additional providers.
Providers further to the right shadow providers to the left, with properties in
the original `opts` being shadows by the new providers.
##### Example
```js
const opts = MyOpts({x: 1})
opts.get('x') // 1
opts.concat({x: 2}).get('x') // 2
opts.get('x') // 1 (original opts object left intact)
```
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