On Thu, May 5, 2011 at 4:30 AM, Igor Stasenko <[email protected]> wrote:
> On 5 May 2011 01:59, Johan Fabry <[email protected]> wrote: > > > > On 04 May 2011, at 17:30, Stéphane Ducasse wrote: > > > >> > >> mariano got a really nice proxy model based on the stratified proxy of > igor (which is in 1.3). > > > > > > Question: could this be used for PHANtom? We are now using Methodwrappers > but there are some issues (fixed in PHANtom). Mariano, Igor, can you explain > the advantages of your model wrt methodwrappers? > > > > Sorry i'm not familiar with methodwrappers. > > The basic model is separation of proxy and handler. Proxy acts only as > a message trap, > while handler is actually responsible for handling messages trapped by > proxy. > > Mariano builds on top of that, because he wants to replace classes > and/or methods with proxies, > and this requires a special handling (class proxy should obey > VM-specific Behavior format, > and method proxy should implement #run:in:as: when installed in method > dictionary ). > > So, i guess that proxies which representing compiled methods could act > similar to method wrappers. > But of course you still have to implement all intall/deinstall > management et al.. > > The only advantage of new proxies comparing to usual proxies based on > #DNU pattern that > they guarantee a clear separation between meta-levels, i.e. even if > you send #doesNotUnderstand: > message to a proxy, this message will be trapped and handled by > handler as any other. > > Yes, and the cool thing is that proxies can intercept ALL messages, not only those that are not understood. Hence, you don't need to subclass from ProtoObject or nil. In addition (I think, I didn't measure) that they are faster because they don't need to the method lookup until getting to the dnu..but I am not sure about this last one. Another problem with the DNU is what Igor say, you are mixing both things: error handling and message trapping. So...when a proxy receives DNU, how do you know if it was a real dnu or because it needs to trap the message? Implementing method wrappers on top of such proxies is a matter of 5 minutes as much as I can see. In fact, in the paper I "implement" method wrappers as an example. You can take a look by Gofer new squeaksource: 'Marea'; package: 'GhostProxies'; package: 'GhostProxiesTests'; load. But remember it is just a prototype ;) The paper is almost finish... cheers -- Mariano http://marianopeck.wordpress.com
