On Sun, Jun 14, 2015 at 2:04 AM, Jan Strube <[email protected]> wrote:
> PPS: Sorry, the segfault actually is unrelated. Nevertheless, I can't
> figure out the right ccall signature.
>
If you are on a new enough version, you can probably try Cxx.jl[1]
Otherwise, you probably need to do the conversion yourself. Have you tried
`Ptr{Ptr{Cchar}}`?[1]
[1] https://github.com/Keno/Cxx.jl
[2]
http://julia.readthedocs.org/en/latest/manual/calling-c-and-fortran-code/?highlight=char**
>
>
> On Sunday, June 14, 2015 at 2:56:34 PM UTC+9, Jan Strube wrote:
>>
>> PS: My current attempt to return a char** from the vector<string> looks
>> like this:
>> I'm converting to a vector<const char*>, then returning the address of
>> the first element.
>>
>> const char* convert(const std::string& s)
>> {
>> return s.c_str();
>> }
>>
>> const char** lcevtgetcollectionnames( void* event ){
>> LCEventImpl* evt = static_cast<LCEventImpl*>(event);
>> const std::vector<std::string>* nameVec = evt->getCollectionNames();
>> std::vector<const char*>* names = new std::vector<const char*>;
>> std::transform(nameVec->begin(), nameVec->end(),
>> std::back_inserter(*names), convert);
>> return &(*names)[0];
>> }
>>
>>
>> On the Julia side I'm trying this signature:
>> ccall((:lcevtgetcollectionnames, "test.dylib"), Ptr{Cstring},
>> (Ptr{Void},), event)
>>
>> But this results in a seg fault
>>
>> signal (11): Segmentation fault: 11
>>
>> lcevtgetcollectionnames at /Users/stru821/Workdir/Julia/test.dylib
>> (unknown line)
>>
>> anonymous at no file:7
>>
>> jl_apply at
>> /Users/vagrant/buildbot/slave/package_osx10_9/build/src/./julia.h:1299
>>
>> jl_parse_eval_all at
>> /Users/vagrant/buildbot/slave/package_osx10_9/build/src/toplevel.c:573
>>
>> jl_load at
>> /Users/vagrant/buildbot/slave/package_osx10_9/build/src/toplevel.c:616
>>
>> include at
>> /Applications/Julia-0.4.0-dev-539c818c4e.app/Contents/Resources/julia/lib/julia/sys.dylib
>> (unknown line)
>>
>> jl_apply at
>> /Users/vagrant/buildbot/slave/package_osx10_9/build/src/./julia.h:1299
>>
>> include_from_node1 at loading.jl:133
>>
>> jl_apply at
>> /Users/vagrant/buildbot/slave/package_osx10_9/build/src/gf.c:1632
>>
>> process_options at
>> /Applications/Julia-0.4.0-dev-539c818c4e.app/Contents/Resources/julia/lib/julia/sys.dylib
>> (unknown line)
>>
>> _start at
>> /Applications/Julia-0.4.0-dev-539c818c4e.app/Contents/Resources/julia/lib/julia/sys.dylib
>> (unknown line)
>>
>> jlcall__start_18703 at
>> /Applications/Julia-0.4.0-dev-539c818c4e.app/Contents/Resources/julia/lib/julia/sys.dylib
>> (unknown line)
>>
>> jl_apply at
>> /Users/vagrant/buildbot/slave/package_osx10_9/build/src/./julia.h:1299
>>
>> true_main at
>> /Applications/Julia-0.4.0-dev-539c818c4e.app/Contents/Resources/julia/bin/julia
>> (unknown line)
>>
>> main at
>> /Applications/Julia-0.4.0-dev-539c818c4e.app/Contents/Resources/julia/bin/julia
>> (unknown line)
>>
>> Segmentation fault: 11
>>
>>
>>
>>
>> On Sunday, June 14, 2015 at 2:43:24 PM UTC+9, Jan Strube wrote:
>>>
>>> Hi,
>>>
>>> I'm trying to wrap the LCIO file format http://lcio.desy.de/ in Julia.
>>> I have a proof of principle working and am starting to add more of the
>>> API.
>>>
>>> What totally stumps me is this signature:
>>> virtual const std::vector< std::string > *
>>> getCollectionNames
>>> <http://lcio.desy.de/v02-04-03/doc/doxygen_api/html/classEVENT_1_1LCEvent.html#a9128a3f65b8a94629c0cf5e77c0194ac>
>>> ()
>>> const =0
>>>
>>> http://lcio.desy.de/v02-04-03/doc/doxygen_api/html/classEVENT_1_1LCEvent.html#a9128a3f65b8a94629c0cf5e77c0194ac
>>>
>>> I've created a C library to call from Julia, so I'm happy to convert the
>>> return type to char**, but I just cannot figure out how to write a ccall
>>> that doesn't segfault.
>>> I've seen various examples how to convert a Julia array of strings to a
>>> char**, but couldn't find anything that converts a char** to Julia types.
>>>
>>> Any help is greatly appreciated.
>>>
>>> Jan
>>>
>>>
