<br><br><div class="gmail_quote">On Thu, Dec 8, 2011 at 9:11 AM, Mariano Martinez Peck <span dir="ltr"><<a href="mailto:marianopeck@gmail.com">marianopeck@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<br><br><br><div class="gmail_quote">On Thu, Dec 8, 2011 at 5:58 PM, Eliot Miranda <span dir="ltr"><<a href="mailto:eliot.miranda@gmail.com" target="_blank">eliot.miranda@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>Hi Marian,<br><br><div class="gmail_quote">On Thu, Dec 8, 2011 at 7:50 AM, Mariano Martinez Peck <span dir="ltr"><<a href="mailto:marianopeck@gmail.com" target="_blank">marianopeck@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>Hi guys. When the finds a methodDict in nil during the method lookup, it sends #cannotInterpret: to the receiver, but starting the methodLookup in the superclass of the class whose method dict was nil.<br>Example, if I have A subclass from B and B has the method dict in nil, if I sent #foo to an instance of A, it will send #cannotInterpret: to such instance but starting the method lookup (of the #cannotInterpret:) in B (the superclass).<br>
<br>Now, when sending #cannotInterpret: aMessage, it sends as parameter an instance of Message. The thing is that in the instVar "lookupClass" it puts the receiver's class. In this example, A. But when you are implementing #cannotInterpret: such info (the lookupClass) is already there, because you DO have the receiver (in self), so you could always do a "self class". In my case, for some proxies I am doing, I would need not the lookupClass, but the class whose methodDict was nil, in this case, B. <br>
</blockquote><div><br></div><div>Not quite. It puts the lookup class in the lookupClass inst var. So if a super send invokes cannotInterpret: lookupClass will hold the superclass of the method in which the send occurred.</div>
</div></blockquote><div><br>Sorry Eliot I couldn't follow you. I don't understand " if a super send invokes cannotInterpret: ". The #cannotInterpret: is only sent by the VM. How do I exactly could do a super send that invokes #cannotInterpret: ? In this example I did with A and B how should that happen?<br>
</div></div></blockquote><div><br></div><div>cannotInterpret:, like doesNotUnderstand: only happen as a result of a send. The system has to send a message before the VM can send cannotInterpret:, right? Specifically cannotInterpret: happens when a send is made to a receiver where a class in the receiver's hierarchy with a nil methodDictionary is found before a class with a methodDicitonary containing the send's selector. The original send can be a normal send (lookup starts in receiver's class) or a super send (lookup starts in the superclass of the method's methodClass).</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="gmail_quote"><div>
<br> </div><blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="gmail_quote">
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>So, questions:<br><br>1) Do I break something if I do this? Am I limiting the solution somehow? it is not always true that I can get the lookupClass while doing "self class" ? is there someone using this hook of #cannotInterpret:?<br>
</blockquote><div><br></div><div>I have no idea. But given the lookupClass it is a simple matter to walk the hierarchy starting at lookupClass, looking for the first nil methodDictionary. This will be the class at which cannotInterpret: was initiated. Isn't this enough?</div>
<div> </div></div></blockquote><div><br>Good idea. It *may* work. I have to see some weird scenarios with the proxies, but I will give it a try, maybe it can work. Thanks for the idea!<br></div></div></blockquote><div><br>
</div><div>proxies are neither here nor there. lookupClass contains the class in which the lookup started. Following this class's superclass chain *will* find the class with the nil merhodDictionary since the VM found it.</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="gmail_quote"><div> </div><blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
2) Ok, I know that I should send an instance of Message with something it is not the lookupClass in the instVar 'lookupClass', but it is a lookupClass in some form ;)<br><br>Thanks in advance,<br clear="all">
<br>-- <br>Mariano<br><a href="http://marianopeck.wordpress.com" target="_blank">http://marianopeck.wordpress.com</a><br><br>
<br></blockquote></div><br><br clear="all"><div><br></div>-- <br>best,<div>Eliot</div><br>
<br></blockquote></div><br><br clear="all"><br>-- <br>Mariano<br><a href="http://marianopeck.wordpress.com" target="_blank">http://marianopeck.wordpress.com</a><br><br>
<br></blockquote></div><br><br clear="all"><div><br></div>-- <br>best,<div>Eliot</div><br>