Improve docs and error messages

Fixes #6
Fixes #8

Author: ericf

README.md

@@ -1,8 +1,8 @@
 # babel-plugin-react-intl
 
-**THIS IS A PREVIEW RELEASE THAT WORKS WITH A FUTURE, UNRELEASED VERSION OF REACT INTL.**
+Extracts string messages for translation from modules that use [React Intl][].
 
-Extracts string messages from React components that use [React Intl][].
+_**Note:** This Babel plugin works with React Intl v2 which is [in development][v2-discussion]._
 
 ## Installation
 
@@ -12,6 +12,10 @@ $ npm install babel-plugin-react-intl
 
 ## Usage
 
+**This Babel plugin only visits ES6 modules which `import` React Intl.**
+
+The default message descriptors for the app's default language will be extracted from: `defineMessages()`, `<FormattedMessage>`, and `<FormattedHTMLMeessage>`; all of which are named exports of the React Intl package.
+
 ### Via `.babelrc` (Recommended)
 
 **.babelrc**
@@ -30,9 +34,11 @@ $ npm install babel-plugin-react-intl
 
 #### Options
 
-- **`messagesDir`**: The target location where the plugin will output a `.json` file corresponding to each component from which React Intl messages were extracted.
+- **`messagesDir`**: The target location where the plugin will output a `.json` file corresponding to each component from which React Intl messages were extracted. If not provided, the extracted message descriptors will only be accessible via Babel's API.
 
-- **`enforceDescriptions`**: Whether or not message declarations _must_ contain a `description` to provide context to translators.
+- **`enforceDescriptions`**: Whether or not message declarations _must_ contain a `description` to provide context to translators. Defaults to: `false`.
+
+- **`moduleSourceName`**: The ES6 module source name of the React Intl package. Defaults to: `"react-intl"`, but can be changed to another name/path to React Intl.
 
 ### Via CLI
 
@@ -42,6 +48,8 @@ $ babel --plugins react-intl script.js
 
 ### Via Node API
 
+The extract message descriptors are available via the `metadata` property on the object returned from Babel's `transform()` API:
+
 ```javascript
 require("babel-core").transform("code", {
   plugins: ["react-intl"]
@@ -50,3 +58,4 @@ require("babel-core").transform("code", {
 
 
 [React Intl]: http://formatjs.io/react/
+[v2-discussion]: https://github.com/yahoo/react-intl/issues/162

package.json

@@ -1,7 +1,7 @@
 {
   "name": "babel-plugin-react-intl",
   "version": "1.0.0-beta-4",
-  "description": "Extracts string messages from modules that use react-intl.",
+  "description": "Extracts string messages for translation from modules that use React Intl.",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/yahoo/babel-plugin-react-intl.git"

src/index.js

@@ -263,8 +263,8 @@ export default function ({Plugin, types: t}) {
                     if (!(messageObj && messageObj.isObjectExpression())) {
                         throw file.errorWithNode(node,
                             `[React Intl] \`${callee.node.name}()\` must be ` +
-                            `called with message descriptor defined via an ` +
-                            `object expression.`
+                            `called with message descriptors defined as ` +
+                            `object expressions.`
                         );
                     }
 
@@ -288,9 +288,9 @@ export default function ({Plugin, types: t}) {
                 let callee = this.get('callee');
 
                 if (referencesImport(callee, moduleSourceName, FUNCTION_NAMES)) {
-                    let firstArg = this.get('arguments')[0];
+                    let messagesObj = this.get('arguments')[0];
 
-                    firstArg.get('properties')
+                    messagesObj.get('properties')
                         .map((prop) => prop.get('value'))
                         .forEach(processMessageObject);
                 }