Squirrel

Hello everyone,

I'm not sure if this has been discussed before, even though I did a search before posting. Anyway here's the long and short of it.

First the short:
Whenever I try returning a pointer to an instance of a derived class I cannot call the base classes members on the returned object.

Permit me to demonstrate by means of the long:

C++ code:
~~~~~~~~
class cBase
{
public:
    cBase() {}
    virtual ~cBase() {}

    const SQChar *Name () {return "cBase";}
    const SQChar *BaseSpecific () {return "Base Specific";}
};

class cDerived : public cBase
{
public:
    cDerived() {}
    virtual ~cDerived() {}

    const SQChar *Name () {return "cDerived";}
    const SQChar *DerivedSpecific () {return "Derived Specific";}
};

DECLARE_INSTANCE_TYPE(cBase)
DECLARE_INSTANCE_TYPE(cDerived)

cBase b;
cDerived d;

cBase &GetBase() {return b;}
cDerived &GetDerived() {return d;}
cBase *GetBasePtr() {return &b;}
cDerived *GetDerivedPtr() {return &d;}

...

SQClassDef<cBase>(_T("cBase"))
    .func(&cBase::Name, _T("Name"))
    .func(&cBase::BaseSpecific, _T("BaseSpecific"));

SQClassDef<cDerived>(_T("cDerived"), _T("cBase"))
    .func(&cDerived::Name, _T("Name"))
    .func(&cDerived::DerivedSpecific, _T("DerivedSpecific"));

RegisterGlobal(&GetBase, _T("GetBase"));
RegisterGlobal(&GetDerived, _T("GetDerived"));
RegisterGlobal(&GetBasePtr, _T("GetBasePtr"));
RegisterGlobal(&GetDerivedPtr, _T("GetDerivedPtr"));

Squirrel Code:
~~~~~~~~~~~
b <- cBase();
print(b.Name() + "\n");
print(b.BaseSpecific() + "\n");
print("b <- cBase() worked perfectly...\n\n");

b <- GetBase();
print(b.Name() + "\n");
print(b.BaseSpecific() + "\n");
print("b <- GetBase() worked perfectly...\n\n");

b <- GetBasePtr();
print(b.Name() + "\n");
print(b.BaseSpecific() + "\n");
print("b <- GetBasePtr() worked perfectly...\n\n");

d <- cDerived();
print(d.Name() + "\n");
print(d.DerivedSpecific() + "\n");
print(d.BaseSpecific() + "\n");
print("d <- cDerived() worked perfectly...\n\n");

d <- GetDerived();
print(d.Name() + "\n");
print(d.DerivedSpecific() + "\n");
print(d.BaseSpecific() + "\n");
print("d <- GetDerived() worked perfectly...\n\n");

d <- GetDerivedPtr();
print(d.Name() + "\n");
print(d.DerivedSpecific() + "\n");
print("but now it's about to fall apart...\n");
print(d.BaseSpecific() + "\n");

Is this similar with the problem reported in: http://wiki.squirrel-lang.org/default.aspx/SquirrelWiki/SqPlusNativeCreatedInstancesWithCorrectAncestry.html?
(Not fixed yet)

Yes, thank you very much, it was the problem and the proposed solution works with MinGW GCC.

Why hasn't the fix been incorporated into the official distribution yet?

Thanks again,
nix

Thank you for your report.  Could you tell me the version of sqplus you've applied the patch to?

> Why hasn't the fix been incorporated into the official distribution yet?

Because we have no organized bug tracking system for SqPlus, it is very
difficult to find the effective patch.  I'm attempting to pick patches from wiki
or forums and to put into the snapshot, but it's still underway.

K. Kawachi

I initially applied the patch to the 20070304 snapshot. Since then I've applied it to the 20070602 snapshot, and everything still seems to work as expected with gcc 3.4.5 (mingw special).


Thanks again for the pointer Katsuaki, my script bindings have become much simpler since I don't have to try work around this problem anymore.

Kind regaurds,
Niki

Hi Niki,

I did some tests around the patched versions.  I found that:

• The patch works well for your test code with gcc and VS.NET
  
• VS.NET (2003 / 2005) can pass your test code without the patch
  
• Tests in "testSqPlus2unit/test_ClassInstance.cpp" fails with the patch

So, for gcc I've made small modification to the original snapshot.
I also added your test code to testSqPlus2unit/test_PointerToDerived.cpp.

Could you please test this modified version of SqPlus with your application?
You can get it from subversion:
 $ svn co https://sqplus.svn.sourceforge.net/svnroot/sqplus/branches/kkawachi-r54-pointer-to-derived

K. Kawachi

Hi Katsuaki,

I'm glad to see you cleaned up my messy test before adding it to the distribution

I've built and tested your latest commit with no ill effects. A few quick tests of my bindings and everything seems to work nicely.

Great job! Thank you,
Niki

I merged the fix into trunk and updated the snapshot of sqplus (20070701).
 http://wiki.squirrel-lang.org/default.aspx/SquirrelWiki/SqPlus.html

Many thanks!