[Pharo-project] Alien callback thunk as ExternalAddress?

Schwab,Wilhelm K bschwab at anest.ufl.edu
Wed Mar 21 21:24:37 EDT 2012


It turns out that I had already done the #fromInteger: game, but your reply/confirmation gave me a brief second wind.  I added #asExternalAddress (doing the obvious thing given your reply) to both callback thunks and to GSL memory objects (handle bodies that have subclasses for vectors, wavelet entrails, etc.). I took one FFI call parameter from long to struct*.  That was interesting, because getHandle asInteger was giving me a *huge* number; the struct* argument worked where long failed me (it's usually the other way around).

I am now at the point of getting an error in a method being called from a callback!!!  That's a nice problem to have :)  Somehow, I have to figure out how to get one of my handle bodies wrapped around an Alien argument.  Whatever I do will also want to work with non-aliens because I call (with some trickery) the same method myself to generate sample data.

As Sig said, the debugger is available inside of callbacks - that's going to be a huge help.  It's time to shut down for the day or I will hate myself in the morning.

More to come.  Thanks!!!!


From: pharo-project-bounces at lists.gforge.inria.fr [pharo-project-bounces at lists.gforge.inria.fr] on behalf of Eliot Miranda [eliot.miranda at gmail.com]
Sent: Wednesday, March 21, 2012 8:18 PM
To: Pharo-project at lists.gforge.inria.fr
Subject: Re: [Pharo-project] Alien callback thunk as ExternalAddress?

On Wed, Mar 21, 2012 at 4:01 PM, Schwab,Wilhelm K <bschwab at anest.ufl.edu<mailto:bschwab at anest.ufl.edu>> wrote:
I am getting near to jumping off the callback cliff.  My problem is that I have a generated external structure that expects a void pointer (actually a function pointer).  The setter sends #getHandle.  I tried to hot-wire that by defining CallbackThunk>>getHandle to answer the #address.

But FFICallbackThunk already implements address (inherited from Alien).  Why getHandle?

Is there a way to get an ExternalAddress that points to the thunk?  Should I even be asking this question? :)

I *think* it should be
    ExternalAddress new fromInteger: anFFICallbackThunk address



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