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    <p>This is the best <a href="http://web.archive.org/web/20150217015842/http://create.tpsitulsa.com/blog/2009/01/29/v8-objects" rel="noreferrer">blog post I could find on exposing C++ objects to V8 Javascript</a>. It goes into deeper detail and breaks it down into smaller steps with code snippets. Be warned: the code snippets have little inconsistencies and it took me several reads to understand. Reading my brief summary beforehand may help:</p> <ol> <li><strong>Objects must be wrapped in V8 templates.</strong> Note: The Google sample uses ObjectTemplates, but the author explains why he prefers FunctionTemplates. <ol> <li>Create a FunctionTemplate. Instances of this template have an internal field to store the memory address of the C++ object. They also get the class' accessor methods.</li> <li>Make a function wrapObject() that will wrap a C++ object in one of these FunctionTemplates.</li> </ol></li> <li><strong>The constructor must also be wrapped in a (different) V8 template.</strong> A different template is used to avoid unwanted recursion. (A method of combining both templates into one is described at the end of the blog post.) <ol> <li>Create another FunctionTemplate. This template simply connects the JavaScript global scope (where <code>new</code> will be called from) to the C++ constructor.</li> <li>Make the method that the template will call. This method actually uses the C++ <code>new</code> operator and calls the C++ class constructor. It then wraps the object by calling the wrapObject() method created in step 1.2.</li> </ol></li> </ol> <hr> <p>Now, the memory allocated in step 2.2 must be <code>delete</code>'d some time. <strong>Update:</strong> The next blog entry, "<a href="http://web.archive.org/web/20140727091841/http://create.tpsitulsa.com/blog/2009/01/31/persistent-handles/" rel="noreferrer">Persistent Handles</a>," covers this in detail.</p> <p>My notes on the <a href="http://bazaar.launchpad.net/~alex.iskander/create/trunk/annotate/head%3A/Script/Source/Environments/V8/V8Context.cpp" rel="noreferrer">actual code alluded to in these blog posts</a>:</p> <ul> <li>The <code>wrapPoint()</code> method in the blog is actually analogous to the <code>unwrap()</code> method in the actual code; <em>not</em> <code>wrap()</code></li> <li>To find other common points between the code, search for: <code>SetInternalFieldCount(0</code>, <code>constructorCall</code></li> <li>The actual code seems to do memory management by using the MakeWeak() method to set a callback method that does the cleanup.</li> </ul>
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    1. POHow do you expose a C++ class in the V8 Javascript Engine so it can be created using new?
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