Re: [PATCH] assortment of problems

Steve Fink wrote:

> I have been having a series of problems when trying to wrap a couple 
> of templatized C++ classes with Perl. I have finally beaten SWIG into 
> submission with a set of patches, all of one of which are attached to 
> this message.
>
> The first patch, which is not attached because it is large, is John 
> Lenz's type system patch at <http://www.cs.wisc.edu/~lenz/swig.html>. 
> I modified it very slightly, however -- both my C++ library and Perl 
> were using the DEBUG macro, and Lenz's patch added yet another use, so 
> I edited the patch to use SWIG_DEBUG instead. I used this patch 
> because it sounded like it might fix my problems. It didn't, but it 
> still seems like a nice improvement. In fact, I think there's a pretty 
> good chance that it ended up providing a large piece of the solution, 
> but I haven't tried going back and applying all my other patches 
> without it in order to find out.
>
> The second patch (SWIG-1.3.21-warnings.diff) just removes a bunch of 
> warnings about incomplete initializers. The problem is present with or 
> without Lenz's patch, but this patch will only apply on top of his 
> stuff since it changes what gets initialized, while still initializing 
> stuff in the same way.
>
> The third patch (SWIG-1.3.21-debug.diff) adds a -debug flag to SWIG to 
> turn on template debugging (it sets the global template_debug 
> variable). It doesn't do it in a pretty way, but I didn't really care.
>
> The fourth patch (SWIG-1.3.21-qual.diff) makes SWIG look for template 
> name matches both without any namespace qualification (as in 
> swig1.3.21) and with it. I had code like:
>
>  namespace std {
>    template<class T, typename A> class vector<T,A>...
>    %define specialize_std_vector(T)
>    template<typename A> class vector<T,A>...
>    %enddef
>  }
>  .
>  .
>  .
>  %template(MyFloatVec)   std::vector<float, MyAllocator<float> >;
>
> That compares 'vector' with 'std::vector' and fails. If I instead say 
> 'std::vector' within the 'namespace std' section, it fails because... 
> I forget, and left my notes at home. But it doesn't work, and saying 
> namespace std { std::vector } just seems redundant anyway.
>
> The fifth patch (SWIG-1.3.21-perlshadow.diff) adds a SWIG_FindType 
> routine that searches through all swig_type_info*'s and calls a 
> user-provided function on them, returning the first one that returns 
> true. Then I use that in the perl*.swg files to lookup 
> swig_type_info's for shadow class names (which are stored in 
> ->clientdata). This is because I couldn't figure out any way of 
> wrapping up a C++ object as a Perl shadow class SV from within C++. I 
> could use QueryType and NewPointerObj to wrap things up as the 
> underlying types, but then they would have no association with the 
> shadow type. This patch requires Lenz's patch because the way you 
> iterate through all swig_type_info*'s is different. I really should 
> break this patch up into two patches, one of which just provides 
> SWIG_FindType and has nothing to do with Perl, and then the 
> Perl-specific stuff. But given my fuzzy understanding of the SWIG 
> internals, I'm guessing it's more likely that these patches won't make 
> any sense to people who actually know what's going on, so I'd rather 
> not go to the effort. (But I'd be interested if someone could clean up 
> my use of the various layers of SWIG_XXX and SWIG_Perl_XXX and 
> SWIGIMPORT() and SWIGRUNTIME() and ...?)
>
> I am also attaching the .spec file I use to generate my SWIG RPM, 
> since it includes these patches and also has some changes to properly 
> build outside of the system RPM area. (The provided .spec file leaks 
> various files into system directories.)
>
> Finally, I should note that some of this will not apply to the current 
> CVS, because it has added some weird A vs B|C|D type equivalency 
> searching that collides with Lenz's patch. I didn't bother to look at 
> why it's needed, because everything is finally working for me (as far 
> as I can tell so far!).

The "B|C" type equivalence is there to solve several problems with 
templates + typedefs + namespaces,
in the example

namespace A {
  struct OpaqueStruct;
  typedef struct OpaqueStruct OpaqueType;
  typedef std::vector<OpaqueType> OpaqueVectorType;

  void FillVector(OpaqueVectorType);
}

it generates

"_p_A__OpaqueVectorType" => "std::vector<A::OpaqueStruct > 
*|A::OpaqueVectorType *"


ie, it keeps the equivalence between "A::OpaqueVectorType" and the fully 
resolved
primitive type "std::vector<A::OpaqueStruct >".

Probably it will also fix some of the problems you are addressing with 
your patches.


Marcelo

> Yes, I know I ought to be filing bugs for all of these things, but 
> I've probably spent far too much time already struggling with this 
> stuff. I'll try to at least put these patches into the tracker.


_______________________________________________
Swig maillist  -  Swig@xxxxxxxxxxxxxxx
http://mailman.cs.uchicago.edu/mailman/listinfo/swig