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[sq 3.0.2] closure cloned instead of assigned on derived class objects(works ok with baseless class)
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nitramc
#1 Posted : Friday, August 03, 2012 9:08:27 PM(UTC)
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I was wondering why a new closure is created when assigning a derived class' function but not when assigning a base.
As you can see in the output below, each assignment creates a new pointer.

I need to change functions during execution, but only if they match the old one.

Code:
Code:


class A {
    function memberfn() { }
}

class D extends A {
    function memberfn() { }
}

function fn() {}


print("A.memberfn="+A.memberfn+"    fn="+fn);
A.memberfn <- fn;
print("A.memberfn="+A.memberfn+"    fn="+fn);
A.memberfn <- fn;
print("A.memberfn="+A.memberfn+"    fn="+fn);

print("D.memberfn="+D.memberfn+"    fn="+fn);
D.memberfn <- fn;
print("D.memberfn="+D.memberfn+"    fn="+fn);
D.memberfn <- fn;
print("D.memberfn="+D.memberfn+"    fn="+fn);


Output:
Code:
A.memberfn=(function : 0x064E1050)    fn=(function : 0x064DA0C0)
A.memberfn=(function : 0x064DA0C0)    fn=(function : 0x064DA0C0)
A.memberfn=(function : 0x064DA0C0)    fn=(function : 0x064DA0C0)

D.memberfn=(function : 0x064E1588)    fn=(function : 0x064DA0C0)
D.memberfn=(function : 0x064D9FC0)    fn=(function : 0x064DA0C0)
D.memberfn=(function : 0x064DFA18)    fn=(function : 0x064DA0C0)


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fagiano
#2 Posted : Monday, August 06, 2012 8:05:39 AM(UTC)
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the closure is cloned to store the base class, this is to implement the 'base' pseudo variable.

ciao
Alberto
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nitramc
#3 Posted : Monday, August 06, 2012 10:37:14 AM(UTC)
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Got it, thanks!

I'll have to keep track of all the clones, I guess...
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nitramc
#4 Posted : Thursday, August 09, 2012 11:24:02 PM(UTC)
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Alberto, is there a way to know the originating function?

I'm guessing the clone just changes free variables/environment but keeps track of a single compiled function.

Even if it's not exported as an API call, could you point me in the right direction so I can hack it?
I'm keeping a map of all equal functions, but this map grows larger and slower with each function reload (I reload a lot of functions)

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fagiano
#5 Posted : Friday, August 10, 2012 5:21:09 AM(UTC)
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maybe I should add a built-in function to compare 2 closures closure.identity() or something like that.
For now you could implement something like that by your own, sq_getfunctioninfo gives you structure that contains a "funcid". funcid is unique across all closures of the same function.

ciao
Alberto
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nitramc
#6 Posted : Monday, August 20, 2012 1:49:27 PM(UTC)
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Thanks for the heads up! I've solved it.
I'll post the code I'm using in case someone else needs it.

NOTES:
* The path to the source code must be added as an additional include path (not the common squirrel path, the one with the .cpp files)
* I made it for Sqrat, but it can be worked out for vanilla squirrel or another binder

Code:
#include <squirrel.h>
#include <sqpcheader.h>
#include <sqvm.h>
#include <sqfuncproto.h>
#include <sqclosure.h>
#include <sqstring.h>
#include <sqclosure.h>
bool s_functionProtosAreEqual(Sqrat::Function fa, Sqrat::Function fb) {
    HSQOBJECT &a = fa.GetFunc(), &b = fb.GetFunc();
    if(!sq_isclosure(a) || !sq_isclosure(b)) return false;
    SQFunctionProto *pa = a._unVal.pClosure->_function;
    SQFunctionProto *pb = b._unVal.pClosure->_function;
    return pa == pb;
}


Code:
Sqrat::RootTable().Func("functionProtosAreEqual", &s_functionProtosAreEqual);
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