feat(proxy-state-tree): expose option to wrap functions in the tree to inject custom stuff

Author: christianalfoni

packages/node_modules/proxy-state-tree/README.md

@@ -138,4 +138,18 @@ const tree = new ProxyStateTree({
 })
 ```
 
-The allows you to easily extend functionality with for example a computed concept that lives in the tree, as you can see in this [codesandbox](https://codesandbox.io/s/xnv45zmkz).
+The allows you to easily extend functionality with for example a computed concept that lives in the tree, as you can see in this [codesandbox](https://codesandbox.io/s/xnv45zmkz).
+
+You can inject a wrapper around this function by:
+
+```js
+import ProxyStateTree from 'proxy-state-tree'
+
+const tree = new ProxyStateTree({
+  foo: (foo, proxyStateTree, path) => {}
+}, {
+  dynamicWrapper: (proxyStateTree, path, func) => func('foo', proxyStateTree, path)
+})
+```
+
+This helps you expose library entities to these functions.

packages/node_modules/proxy-state-tree/src/index.test.ts

@@ -369,6 +369,23 @@ describe('FUNCTIONS', () => {
     }
     const tree = new ProxyStateTree(state)
 
+    expect(tree.get().foo).toBe('bar')
+  })
+  test('should be able to inject a wrapper around functions', () => {
+    const state = {
+      foo: (foo, proxyStateTree, path) => {
+        expect(foo).toBe('foo')
+        expect(proxyStateTree).toBe(tree)
+        expect(path).toEqual('foo')
+
+        return 'bar'
+      },
+    }
+    const tree = new ProxyStateTree(state, {
+      dynamicWrapper: (proxyStateTree, path, func) =>
+        func('foo', proxyStateTree, path),
+    })
+
     expect(tree.get().foo).toBe('bar')
   })
 })

packages/node_modules/proxy-state-tree/src/index.ts

@@ -2,7 +2,8 @@ import proxify, { IS_PROXY, STATUS } from './proxify'
 const isPlainObject = require('is-plain-object')
 
 export type Options = {
-  devmode: boolean
+  devmode?: boolean
+  dynamicWrapper?: Function
 }
 
 type Mutation = {
@@ -21,11 +22,15 @@ class ProxyStateTree {
   paths: Set<string>[]
   status: STATUS
   proxy: any
-  constructor(state: object, options: Options = { devmode: true }) {
+  constructor(state: object, options: Options = {}) {
     if (!isPlainObject(state)) {
       throw new Error('You have to pass a plain object to the Proxy State Tree')
     }
 
+    if (typeof options.devmode === 'undefined') {
+      options.devmode = true
+    }
+
     this.state = state
     this.options = options
     this.pathDependencies = {}

packages/node_modules/proxy-state-tree/src/proxify.ts

@@ -112,7 +112,9 @@ function createObjectProxy(tree, value, path) {
       }
 
       if (typeof targetValue === 'function') {
-        return targetValue(tree, nestedPath)
+        return tree.options.dynamicWrapper
+          ? tree.options.dynamicWrapper(tree, nestedPath, targetValue)
+          : targetValue(tree, nestedPath)
       }
 
       if (targetValue === undefined) {