On 31 Jan 2006, at 19:40, David Abrahams wrote:
Stefan Roiser <stefan.roiser@cern.ch> writes:
On 30 Jan 2006, at 17:08, Stefan Seefeld wrote:
With interaction with objects I meant e.g. through the meta-level instantiate a class, get/set the data member values, call a function on that instance, retrieve the function's return value and so on. I may have missed that, but I couldn't find examples on the synopsis page for this functionality.
Reflex code for this would look something like
Type t = Type::ByName("foo"); Object instance = t.Construct(); Object ret_obj = instance.Invoke("myFunction");
Very interesting. Where do you get the object code for foo::myFunction? Or have you implemented a full C++ interpreter?
foo::myFunction will be invoked through a stub function which is part of the dictionary library for class foo. A dictionary library may be dynamically loaded in a program. The source code for this dictionary library is produced in a non- intrusive way with a python script (genreflex.py). Besides the stub functions this dictionary source code contains the information about all types, scopes, members one wants to generate the reflection information for. To give you an idea, typically this automatically produced code would look like (this is part of the code for the example class of my first mail) static void* constructor_3558( void* mem, const std::vector<void*>& arg, void*) { return ::new(mem) ::zot::foo(*(const ::zot::foo*)arg[0]); } static void* constructor_3559( void* mem, const std::vector<void*>&, void*) { return ::new(mem) ::zot::foo(); } static void* destructor_3560(void * o, const std::vector<void*>&, void *) { ((::zot::foo*)o)->~foo(); return 0; } static void* method_3561( void* o, const std::vector<void*>&, void*) { static int ret; ret = ((::zot::foo*)o)->bar(); return &ret; } ...... void __zot__foo_dict() { ClassBuilder("zot::foo", typeid(zot::foo), sizeof(zot::foo), PUBLIC | CLASS) .AddBase(type_2263, BaseOffset< ::zot::foo, ::zot::foo_base >::Get (), VIRTUAL | PUBLIC) .AddFunctionMember(FunctionTypeBuilder(type_void, type_4260), "foo", constructor_3558, 0, "_ctor_arg", PUBLIC | ARTIFICIAL | CONSTRUCTOR) .AddFunctionMember(FunctionTypeBuilder(type_void), "foo", constructor_3559, 0, 0, PUBLIC | ARTIFICIAL | CONSTRUCTOR) .AddFunctionMember(FunctionTypeBuilder(type_void), "~foo", destructor_3560, 0, 0, PUBLIC | ARTIFICIAL | DESTRUCTOR ) .AddFunctionMember(FunctionTypeBuilder(type_9), "bar", method_3561, 0, 0, PUBLIC) ......
Have you considered something like the object interface of Boost.Python?
Type t = Type::ByName("foo"): Object instance = t(); Object ret_obj = instance.member("myFunction")();
Then you'd also have, e.g.
Object enlarged = instance & 5;
To be frank - no, but this is a very good idea. Thx for the input!
-- Dave Abrahams Boost Consulting www.boost-consulting.com
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-- Stefan Roiser CERN, PH Department CH - 1211 Geneva 23 Mob:+41 76 487 5334 Tel:+41 22 767 4838 Fax:+41 22 767 9425