Allow Base cast specialization

[GoogleCodeExporter]

This is not a bug but a feature request

I love the builtin casting ability of Base, but there are situations where I 
would like to customize coercion.  I have enclosed a small patch to enhance 
Base with this ability.  

Basically, it will look for a static coerce method in the class or its 
ancestors.  If one is found, it is called and the return value is used as the 
cast.  Otherwise, the default casting is performed. 


What version of the product are you using? On what operating system?
Currently on Mac OS X 10.9.4

Here is the diff (attached as well)

Index: base2/Base.js
===================================================================
--- base2/Base.js   (revision 310)
+++ base2/Base.js   (working copy)
@@ -23,6 +23,12 @@
         delete this.__constructing;
       } else {
         // Casting.
+        var coerce = _class;
+        do {
+          if (coerce.coerce)
+            return coerce.coerce.call(_class, arguments[0]);
+          coerce = coerce.ancestor;
+        } while (coerce && (coerce != Base));
         return extend(arguments[0], _prototype);
       }
     }

Original issue reported on code.google.com by [email protected] on 14 Jul 2014 at 6:56

Attachments:

• coerce.diff

[GoogleCodeExporter]

Here is a minor tweak that will fall through to default cast if no coercion is 
performed

Index: Base.js
===================================================================
--- Base.js (revision 310)
+++ Base.js (working copy)
@@ -23,6 +23,13 @@
         delete this.__constructing;
       } else {
         // Casting.
+        var cls = _class;
+        do {
+          if (cls.coerce) {
+            var cast = cls.coerce.call(_class, arguments[0]);
+            if (cast) return cast;
+          }
+        } while ((cls = cls.ancestor) && (cls != Base));
         return extend(arguments[0], _prototype);
       }
     }

Original comment by [email protected] on 15 Jul 2014 at 12:11

Attachments:

• coerce.diff