deprecate context.history and context.location

refs remix-run#2646

Author: ryanflorence

.eslintrc

@@ -1,5 +1,8 @@
 {
   "extends": "rackt",
+  "globals": {
+    "__DEV__": true
+  },
   "rules": {
     "react/jsx-uses-react": 1,
     "react/jsx-no-undef": 2,

modules/RoutingContext.js

@@ -1,3 +1,4 @@
+import deprecateObjectProperties from './deprecateObjectProperties'
 import invariant from 'invariant'
 import React, { Component } from 'react'
 import { isReactChildren } from './RouteUtils'
@@ -23,7 +24,10 @@ class RoutingContext extends Component {
         return history.isActive(...args)
       }
     }
-    return { history, location, router }
+    return deprecateObjectProperties({ history, location, router }, {
+      history: '`context.history` is deprecated, please use context.router',
+      location: '`context.location` is deprecated, please use a route component\'s `props.location` instead. If this is a deeply nested component, please refer to the strategies described in https://github.com/rackt/react-router/blob/v1.1.0/CHANGES.md#v110'
+    })
   }
 
   createElement(component, props) {

modules/deprecateObjectProperties.js

@@ -0,0 +1,34 @@
+/*eslint no-empty: 0*/
+import warning from 'warning'
+
+let useMembrane = false
+
+if (__DEV__) {
+  try {
+    Object.defineProperty({}, 'x', { get() { return true } }).x
+    useMembrane = true
+  } catch(e) { }
+}
+
+// wraps an object in a membrane to warn about deprecated property access
+export default function deprecateObjectProperties(object, deprecatedKeys) {
+  if (!useMembrane)
+    return object
+
+  const membrane = {}
+
+  for (let prop in object) {
+    Object.defineProperty(membrane, prop, {
+      configurable: false,
+      enumerable: true,
+      get() {
+        if (deprecatedKeys[prop])
+          warning(!deprecatedKeys[prop], deprecatedKeys[prop])
+        return object[prop]
+      }
+    })
+  }
+
+  return membrane
+}
+