Author: [email protected]
Date: Mon Mar 9 05:50:32 2009
New Revision: 1451
Modified:
branches/bleeding_edge/src/messages.js
Log:
Added .message accessor to messages. This gives you the same
descriptive message as is used to construct the toString() for an
error object.
Modified: branches/bleeding_edge/src/messages.js
==============================================================================
--- branches/bleeding_edge/src/messages.js (original)
+++ branches/bleeding_edge/src/messages.js Mon Mar 9 05:50:32 2009
@@ -153,7 +153,7 @@
args = [];
}
- var e = new constructor();
+ var e = new constructor(kAddMessageAccessorsMarker);
e.type = type;
e.arguments = args;
return e;
@@ -589,6 +589,29 @@
//
----------------------------------------------------------------------------
// Error implementation
+// If this object gets passed to an error constructor the error will
+// get an accessor for .message that constructs a descriptive error
+// message on access.
+var kAddMessageAccessorsMarker = { };
+
+// Defines accessors for a property that is calculated the first time
+// the property is read and then replaces the accessor with the value.
+// Also, setting the property causes the accessors to be deleted.
+function DefineOneShotAccessor(obj, name, fun) {
+ // Note that the accessors consistently operate on 'obj', not 'this'.
+ // Since the object may occur in someone else's prototype chain we
+ // can't rely on 'this' being the same as 'obj'.
+ obj.__defineGetter__(name, function () {
+ var value = fun(obj);
+ obj[name] = value;
+ return value;
+ });
+ obj.__defineSetter__(name, function (v) {
+ delete obj[name];
+ obj[name] = v;
+ });
+}
+
function DefineError(f) {
// Store the error function in both the global object
// and the runtime object. The function is fetched
@@ -607,7 +630,13 @@
f.prototype.name = name;
%SetCode(f, function(m) {
if (%IsConstructCall()) {
- if (!IS_UNDEFINED(m)) this.message = ToString(m);
+ if (m === kAddMessageAccessorsMarker) {
+ DefineOneShotAccessor(this, 'message', function (obj) {
+ return FormatMessage({type: obj.type, args: obj.arguments});
+ });
+ } else if (!IS_UNDEFINED(m)) {
+ this.message = ToString(m);
+ }
} else {
return new f(m);
}
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