<br><br><div class="gmail_quote">On Fri, Apr 1, 2011 at 5:51 AM, Javier Pimás <span dir="ltr"><<a href="mailto:elpochodelagente@gmail.com">elpochodelagente@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, this method of Interpreter is used for debugging, and should print the name of the class passed in console:<div><br></div><div><div>printNameOfClass: classOop count: cnt</div><div><span style="white-space:pre-wrap"> </span>"Details: The count argument is used to avoid a possible infinite recursion if classOop is a corrupted object."</div>
<div><br></div><div><span style="white-space:pre-wrap"> </span>cnt <= 0 ifTrue: [ ^ self print: 'bad class' ].</div><div><span style="white-space:pre-wrap"> </span>(self sizeBitsOf: classOop) = (7 * self bytesPerWord)<span style="white-space:pre-wrap"> </span>"(Metaclass instSize+1 * 4)"</div>
<div><span style="white-space:pre-wrap"> </span>ifTrue: [self printNameOfClass: (self fetchPointer: 5 "thisClass" ofObject: classOop) </div><div><span style="white-space:pre-wrap"> </span>count: cnt - 1.</div>
<div><span style="white-space:pre-wrap"> </span>self print: ' class']</div><div><span style="white-space:pre-wrap"> </span>ifFalse: [self printStringOf: (self fetchPointer: 6 "name" ofObject: classOop)]</div>
<div><br></div><div>it's logic is this: if the classOop is of a normal Class instance, it should use the instance var number six,<br> </div></div></blockquote><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div><div>which corresponds to the class' name. If not, then the classOop represents a Metaclass instance, and then it will fetch inst var number 5, which is the corresponding class, print its name, and then print 'class' to let you distinguish it that it is a metaclass.</div>
</div></blockquote><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div>
<div><br></div><div>The problem of the method is that it determines if it's a class instance or a metaclass instance by looking at the size of the oop, which seems to have changed, at least in pharo (Metaclass instSize+1 * 4 = 36 = 9*bytesPerWord). </div>
</div></blockquote><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div>
<div><br></div><div>The method could be fixed by changing 7 to 9 then. But it will break if Metaclass changes again. </div></div></blockquote><div><br>yes<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><div>So I have this idea: make it check if the classOop is a metaclass instance. Metaclass class is not a special object, but can be obtained by accessing any special one, like with </div>
<div><br></div><div>Integer class class</div><div><br></div><div>or directly with</div><div><br></div><div>nil class class class (!!)</div><div><br></div><div>then the proposed code is:</div><div><br></div><div><span style="white-space:pre-wrap">printNameOfClass: classOop count: cnt
"Details: The count argument is used to avoid a possible infinite recursion if classOop is a corrupted object."
| metaclassClass |
cnt <= 0 ifTrue: [ ^ self print: 'bad class' ].
metaclassClass := self fetchClassOf: (self fetchClassOf: (self fetchPointer: ClassInteger ofObject: specialObjectsOop)).
metaclassClass = (self fetchClassOf: classOop) "Is it a metaclass?"
ifTrue: [self printNameOfClass: (self fetchPointer: 5 "thisClass" ofObject: classOop)
count: cnt - 1.
self print: ' class']
ifFalse: [self printStringOf: (self fetchPointer: 6 "name" ofObject: classOop)]</span></div><div><br></div></div></blockquote><div><br><br>Looking at Cog, I think Eliot has already solved this problem:<br><br>
printNameOfClass: classOop count: cnt<br> "Details: The count argument is used to avoid a possible infinite recursion if classOop is a corrupted object."<br> <inline: false><br> (classOop = 0 or: [cnt <= 0]) ifTrue: [^self print: 'bad class'].<br>
((objectMemory sizeBitsOf: classOop) = <span style="background-color: rgb(255, 255, 51);">metaclassSizeBytes</span><br> and: [metaclassSizeBytes > (<span style="background-color: rgb(255, 255, 51);">thisClassIndex</span> * BytesPerWord)]) "(Metaclass instSize * 4)"<br>
ifTrue: [self printNameOfClass: (objectMemory fetchPointer: <span style="background-color: rgb(255, 255, 51);">thisClassIndex</span> ofObject: classOop) count: cnt - 1.<br> self print: ' class']<br>
ifFalse: [self printStringOf: (objectMemory fetchPointer: <span style="background-color: rgb(255, 255, 51);">classNameIndex</span> ofObject: classOop)]<br><br><br>And metaclassSizeBytes is set in a "similar" way you proposed:<br>
<br>StackInterpreter >> initializeExtraClassInstVarIndices<br> "Initialize metaclassSizeBytes and thisClassIndex which are used in debug printing, and<br> classNameIndex which is used not only for debug printing but for is:KindOf: & is:MemberOf:<br>
via classNameOf:is: (evil but a reality we have to accept)."<br> | classArrayObj classArrayClass |<br><span style="background-color: rgb(255, 255, 51);"> classNameIndex := 6. "default"</span><br style="background-color: rgb(255, 255, 51);">
<span style="background-color: rgb(255, 255, 51);"> thisClassIndex := 5. "default"</span><br> classArrayObj := objectMemory splObj: ClassArray.<br> classArrayClass := objectMemory fetchClassOfNonInt: classArrayObj.<br>
<span style="background-color: rgb(255, 255, 51);"> metaclassSizeBytes := objectMemory sizeBitsOf: classArrayClass. "determine actual (Metaclass instSize * 4)"</span><br> ......<br><br><br>So...it is correct to assume that this is solved in Cog ?<br>
<br>Thanks<br><br>Mariano<br><br><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><div></div><div><br></div><div>I'd also like to have this included too:</div>
<div><br></div><div><div>printClassOf: oop</div>
<div><span style="white-space:pre-wrap"> </span>"Print the class of the oop in console"</div><div><span style="white-space:pre-wrap"> </span>self printNameOfClass: (self fetchClassOf: oop) count: 5. </div>
</div><div><br></div><div>which is simple but pretty much useful.</div><div><br></div><div>What do you think?</div><div><br></div><div>Regards,</div><div> Javier.</div><br>-- <br>Javier Pimás<br>Ciudad de Buenos Aires<br>
</div>
<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>