Warn against all expression errors, add "warnExpressionErros" config option.

(ref #639)

Author: yyx990803

src/config.js

@@ -48,6 +48,13 @@ module.exports = {
 
   async: true,
 
+  /**
+   * Whether to warn against errors caught when evaluating
+   * expressions.
+   */
+
+  warnExpressionErrors: true,
+
   /**
    * Internal flag to indicate the delimiters have been
    * changed.

src/parsers/path.js

@@ -225,10 +225,7 @@ function formatAccessor(key) {
  */
 
 exports.compileGetter = function (path) {
-  var body =
-    'try{return o' +
-    path.map(formatAccessor).join('') +
-    '}catch(e){};'
+  var body = 'return o' + path.map(formatAccessor).join('')
   return new Function('o', body)
 }
 

src/util/debug.js

@@ -9,6 +9,7 @@ var config = require('../config')
 enableDebug()
 
 function enableDebug () {
+
   var hasConsole = typeof console !== 'undefined'
 
   /**
@@ -29,17 +30,20 @@ function enableDebug () {
    * @param {String} msg
    */
 
+  var warned = false
   exports.warn = function (msg) {
-    if (hasConsole && !config.silent) {
+    if (hasConsole && (!config.silent || config.debug)) {
+      if (!config.debug && !warned) {
+        warned = true
+        console.log(
+          'Set `Vue.config.debug = true` to enable debug mode.'
+        )
+      }
       console.warn('[Vue warn]: ' + msg)
       /* istanbul ignore if */
       if (config.debug) {
         /* jshint debug: true */
         debugger
-      } else {
-        console.log(
-          'Set `Vue.config.debug = true` to enable debug mode.'
-        )
       }
     }
   }

src/watcher.js

@@ -77,10 +77,12 @@ p.get = function () {
   try {
     value = this.getter.call(vm, vm)
   } catch (e) {
-    _.warn(
-      'Error when evaluating expression "' +
-      this.expression + '":\n   ' + e
-    )
+    if (config.warnExpressionErrors) {
+      _.warn(
+        'Error when evaluating expression "' +
+        this.expression + '":\n   ' + e
+      )
+    }
   }
   // "touch" every property so they are all tracked as
   // dependencies for deep watching
@@ -106,10 +108,12 @@ p.set = function (value) {
   try {
     this.setter.call(vm, vm, value)
   } catch (e) {
-    _.warn(
-      'Error when evaluating setter "' +
-      this.expression + '":\n   ' + e
-    )
+    if (config.warnExpressionErrors) {
+      _.warn(
+        'Error when evaluating setter "' +
+        this.expression + '":\n   ' + e
+      )
+    }
   }
 }
 

test/unit/specs/parsers/expression_spec.js

@@ -3,16 +3,7 @@ var _ = require('../../../../src/util')
 
 var testCases = [
   {
-    // simple path that doesn't exist
-    exp: 'a.b.c',
-    scope: {
-      a: {}
-    },
-    expected: undefined,
-    paths: ['a']
-  },
-  {
-    // simple path that exists
+    // simple path
     exp: 'a.b.d',
     scope: {
       a:{b:{d:123}}