Re: [boost] Is there any interest in a library which solves C++ class reflection feature just like Java does?

Subject: Re: [boost] Is there any interest in a library which solves C++ class reflection feature just like Java does?
From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2011-12-06 11:46:05

> In brief, I'd designed and implemented somehow C++ class reflection based
> on boost libraries.
> It has some unique advantages:
> a) it doesn't require code generator
> b) platform independent and compiler independent (I tested it on Windows
> and Linux, with vs2008 and gcc respectively)
> c) it's non-intrusive for the class definition, instead, you just need to
> declare and describe your class via some straightforward macros anywhere
> (header file or source file, and may be within any namespace), which also
> means you can wrap an external third-party library (which you have no way
> to touch the source codes) and reflects it classes.
> d) Cross shared library boundary, you can dynamic load the shared library
> and reflect the classes within it, without need to export any symbol
> manunally in C wrapper function way
> e) the API looks like Java reflection API

I'm interested, could we see the sources, please?

Regards Hartmut
---------------
http://boost-spirit.com
http://stellar.cct.lsu.edu

> 
> Below is some codes snippet to have an overview of this library:
> -----libTest.cpp---start---
> #include <iostream>
> #include <string>
> 
> #include <boost/reflection/reflection.hpp>
> 
> namespace test {
> 
> class AccountItf {
> public:
>     virtual std::string getId() const = 0;
>     virtual void setId(std::string id) = 0; };
> 
> #define ACCOUNT_INTERFACE_REFL_DECLARE \
>     BOOST_REFL_INTERFACE(test::AccountItf) \
>     BOOST_REFL_CONST_METHOD(getId, std::string()) \
>     BOOST_REFL_METHOD(setId, void(std::string))
> 
> class Account : public AccountItf {
>     std::string id;
> public:
>     Account() : age(0) {}
>     Account(std::string id, unsigned int age) : id(id), age(age) {}
>     static void echo(Account* acct, std::string banner) {
>         std::cout << banner + ": " << acct->getId() << std::endl;
>     }
>     std::string getId() const {
>         return id;
>     }
>     void setId(std::string id) {
>         this->id = id;
>     }
> public:
>     unsigned int age;
> };
> 
> //Account declaration for used by reflection //this declaration can be
> placed anywhere, even the header file BOOST_REFL_CLASS (
>     (test)(Account),
>     //constructors
>     BOOST_REFL_CONSTRUCTOR()
>     BOOST_REFL_CONSTRUCTOR(std::string id, unsigned int age)
>     //static methods
>     BOOST_REFL_STATIC_METHOD(echo, void (Account* acct, std::string
> banner))
>     //properties
>     BOOST_REFL_PROPERTY(age, unsigned int)
>     //derived Inteface
>     ACCOUNT_INTERFACE_REFL_DECLARE
> )
> }
> 
> -----libTest.cpp----end--
> Compile the libTest.cpp into the libTest.dll or libTest.so.
> 
> -----main.cpp----start--
> #include <iostream>
> #include <string>
> using namespace std;
> 
> #include <boost/reflection/reflection.hpp> using namespace
> boost::reflection;
> 
> #if defined(BOOST_WINDOWS)
> #include <Windows.h>
> #else
> #include <dlfcn.h>
> #endif
> 
> int main(int argc, char* argv[])
> {
> #if defined(BOOST_WINDOWS)
>     LoadLibraryA (argv[1]);
> #else
>     dlopen(argv[1], RTLD_NOW);
> #endif
>     Class t = Class::forName("test.Account");
> 
>     boost::any obj = t.newInstance(std::string("Account-id-100"),
> (unsigned int)26);
> 
>     t.invokeStatic("echo", obj, std::string("TEST"));
> 
>     TypeInfoArray tArray;
>     tArray.push_back(BOOST_REFL_TYPEID(std::string));
>     Method m1 = t.getMethod("setId", tArray);
>     m1.invoke(obj, std::string("Account-id-200"));
> 
>     Method m2 = t.getMethod("getId");
>     boost::any ret = m2.invoke(obj);
>     std::cout << "Account getId(): " << boost::any_cast<std::string>(ret)
> << std::endl;
> 
>     Property prop = t.getProperty("age");
>     prop.set(obj, (unsigned int)30);
>     std::cout << "Account age: " << boost::any_cast<unsigned
> int>(prop.get(obj)) << std::endl;
> 
>     return 0;
> }
> -----main.cpp---end---
> 
> Compile the main.cpp into the executable and execute it:
> ./main libTest.dll
> 
> it will output:
> TEST: Account-id-100
> Account getId(): Account-id-200
> Account age: 30
> 
> 
> This library is very useful for framework-level design which needs C++
> reflection, e.g. recently I'm working on somehow SQL mapping library for
> C++, just like MyBatis, and reflection makes possible to invoke the
> getter/setter of the object instances of classes specified in the XML
> file.
> 
> Regards,
> JinHua
> 
> _______________________________________________
> Unsubscribe & other changes:
> http://lists.boost.org/mailman/listinfo.cgi/boost