CODEWITHSUNDEEP
apache-flexavm2
Richard Szalay
Richard Szalay

Reputation: 84754

Subclassing a private (support) class in AVM2

I am developing a dynamic mocking framework for Flex/AS3 and am having trouble with private/support types (ie. those declared outside the package {} in a class file).

In my ABC "file", I am declaring the instance with the PROTECTED_NAMESPACE class flag and with a PRIVATE_NS multiname. I have also experimented with giving it the same namespace as the class it is subclassing (eg. PRIVATE_NS("ContainerClass.as$123")).

No matter what I do, I always get the following error after loadBytes:

VerifyError: Error #1014: Class ContainerClass.as$123::PrivateClass could not be found.

I have experimented with loading the generated bytecode into the same ApplicationDomain as the private class (I use a child domain by default). I even tried registering a class alias before the load (though that was a bit of a stretch).

Am I forgetting anything or is it simply a restriction of the AVM?

Please note that I am fully aware that this is illegal in ActionScript 3.0, I am looking for whether this is actually possible in the AVM.

Edit: For those interested in the work so far, the project is asmock and is on sourceforge.

Upvotes: 7

Views: 902

Answers (3)

Richard Szalay
Richard Szalay

Reputation: 84754

Having gone back to look at this problem in ernest, I can definitively answer this question: private classes can only be referenced from the LoaderContext that loaded them

I have been able to add support for private interfaces by reproducing the interface in the loaded ABC 'file', but it cannot be coerced/cast back to the original private interface.

This is still useful for my requirements, as a private interface can be used to combine multiple interfaces.

Upvotes: 0

Simon Buchan
Simon Buchan

Reputation: 13245

I'm not sure what you mean by PRIVATE_NS("ContainerClass.as$123"), My reading of avm2overview.pdf 4.4.1 is that private namespaces are not permitted to have a name, hence that the "<class name>$<number>" namespace in debug output is generated for your convenience. I would assume that would mean you would have to hack your abc into the same abc tag in the source swf to access the namespace constant index (and that sounds too much like hard work to me!)

I haven't actually managed to generate a loading swf, though, so take this with a grain of salt.

Upvotes: 1

Christophe Herreman
Christophe Herreman

Reputation: 16085

I'm no expert with ABC files but I just don't think this is possible in the AVM2. I did several tests a while ago with the AS3 Eval lib and they all failed.

Related to dynamic mocking, I have filed an issue in Adobe bugbase, asking for a dynamic proxy mechanism: http://bugs.adobe.com/jira/browse/ASC-3136

Upvotes: 1

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