[cffi-devel] C++ Exceptions.
First, thanks for making this system, and apologies if this isn;t the list for these questions but there appears to be no cffi-users list. In any case, is there any way to catch the underlying c++ exceptions within a cffi-wrapper? I have developed a C++ library that defines its own exceptions and I would like to trap them and generate an appropriate Lisp Condition. At present deliberately triggering an error (say by passingincorrect parameters to a constructor) gives me back a null pointer. Thanks, Collin Lynch.
At Mon, 12 Feb 2007 04:52:51 -0500 (EST), Collin Lynch wrote:
First, thanks for making this system, and apologies if this isn;t the list for these questions but there appears to be no cffi-users list.
In any case, is there any way to catch the underlying c++ exceptions within a cffi-wrapper? I have developed a C++ library that defines its own exceptions and I would like to trap them and generate an appropriate Lisp Condition. At present deliberately triggering an error (say by passingincorrect parameters to a constructor) gives me back a null pointer.
Btw, do you call out to your library, or you plan to just generate exceptions? If you do call out, how do you manage it? I mean, C++ name mangling is hard to keep with, etc...
Thanks, Collin Lynch.
regards, Samium Gromoff
First, thanks for making this system, and apologies if this isn;t the list for these questions but there appears to be no cffi-users list.
In any case, is there any way to catch the underlying c++ exceptions within a cffi-wrapper? I have developed a C++ library that defines its own exceptions and I would like to trap them and generate an appropriate Lisp Condition. At present deliberately triggering an error (say by passingincorrect parameters to a constructor) gives me back a null pointer.
Btw, do you call out to your library, or you plan to just generate exceptions?
If you do call out, how do you manage it?
I mean, C++ name mangling is hard to keep with, etc...
I call out the library using the cffi foreign-function wrapper. as per the example in the cffi manual. What I ended up doing was making use of SWIG. Swig can both parse C++ and generate CFFI wrappers and so I called it to generate the wrappers. However the existing code in swig has issues so I was forced to hand-edit some of it. It succeeded in handling the name-mangling and so on but its attempted clos wrapper for the C++ had one distinct problem, every method had an extra argument. It duitifully generated a wrapper for the exception class that I defined in C++ however objects of that instance are not, seemingly, returned by the library at points where they should be. Rather I get (what appears to be) a null pointer instead. I have not yet explored the potential for trapping that pointer as an exception however.
Thanks, Collin Lynch.
regards, Samium Gromoff
Felicitations, Collin Lynch.
On 12/02/07, Collin Lynch <collinl@cs.pitt.edu> wrote:
In any case, is there any way to catch the underlying c++ exceptions within a cffi-wrapper? I have developed a C++ library that defines its own exceptions and I would like to trap them and generate an appropriate Lisp Condition. At present deliberately triggering an error (say by passingincorrect parameters to a constructor) gives me back a null pointer.
C++ support would be nice. I don't personally have a need for it, but it would be nice. Patches are welcome! :-) The best I can do is point you at Verrazano <http://common-lisp.net/project/fetter/>. Rayiner had some ideas on how to access C++ libraries and there's some code too I believe. Otherwise, you can handle exceptions and other C++ stuff by writing some C glue and calling that with CFFI. -- Luís Oliveira http://student.dei.uc.pt/~lmoliv/
On Mon, 2007-02-12 at 16:44 +0000, Luís Oliveira wrote:
On 12/02/07, Collin Lynch <collinl@cs.pitt.edu> wrote:
In any case, is there any way to catch the underlying c++ exceptions within a cffi-wrapper? I have developed a C++ library that defines its own exceptions and I would like to trap them and generate an appropriate Lisp Condition. At present deliberately triggering an error (say by passing incorrect parameters to a constructor) gives me back a null pointer.
C++ support would be nice. I don't personally have a need for it, but it would be nice. Patches are welcome! :-)
Personally, I consider C++ so deliberately hostile to interfacing with other languages that I'm not sure I'd even want to be responsible for maintaining code for binding to C++ libraries. As I understand it, there's not even a platform ABI that one can try to conform to---things like C++ exception handling and name mangling differ not only per-compiler, but vary depending on the version of the compiler being used. (ISTR maybe they did this for amd64? But I don't think there is in the general case...)
Otherwise, you can handle exceptions and other C++ stuff by writing some C glue and calling that with CFFI.
Unfortunately I think this is the most sane way to go at this point. I suppose another option would be some kind of standard network object protocol like CORBA, but that's a whole separate mess... James
As I said in another e-mail I made use of SWIG's C++ parsing by having it generate the wrapper code. It did fine on that score but had issues with the generated Clos code forcing me to hand-edit the result. Collin Lynch. On Mon, 12 Feb 2007, James Bielman wrote:
On Mon, 2007-02-12 at 16:44 +0000, Luís Oliveira wrote:
On 12/02/07, Collin Lynch <collinl@cs.pitt.edu> wrote:
In any case, is there any way to catch the underlying c++ exceptions within a cffi-wrapper? I have developed a C++ library that defines its own exceptions and I would like to trap them and generate an appropriate Lisp Condition. At present deliberately triggering an error (say by passing incorrect parameters to a constructor) gives me back a null pointer.
C++ support would be nice. I don't personally have a need for it, but it would be nice. Patches are welcome! :-)
Personally, I consider C++ so deliberately hostile to interfacing with other languages that I'm not sure I'd even want to be responsible for maintaining code for binding to C++ libraries.
As I understand it, there's not even a platform ABI that one can try to conform to---things like C++ exception handling and name mangling differ not only per-compiler, but vary depending on the version of the compiler being used. (ISTR maybe they did this for amd64? But I don't think there is in the general case...)
Otherwise, you can handle exceptions and other C++ stuff by writing some C glue and calling that with CFFI.
Unfortunately I think this is the most sane way to go at this point.
I suppose another option would be some kind of standard network object protocol like CORBA, but that's a whole separate mess...
James
participants (4)
-
Collin Lynch -
James Bielman -
Luís Oliveira -
Samium Gromoff