C++ reflection library with Lua binding, and JSON and XML serialisation.

My code tries to declare a class which has a std::string property.

Class::declare<Project>("projects") 
  .constructor<>()   
  .property("name", &Project::getname, &Project::setname) ;

The code compiled but it threw classNotFound exception on classByTypestd::string() at runtime for some reason.

#0  0x00007ffff1c32c1d in __cxa_throw () from /lib64/libstdc++.so.6
#1  0x00007ffff290ad9f in ponder::detail::ClassManager::getById (
    this=0x7ffff2b43900 <ponder::detail::ClassManager::instance()::cm>, id=...)
    at /scratch/backup/ponder/src/classmanager.cpp:99
#2  0x00000000005258cc in ponder::classByType<std::string> ()
    at include/ponder/classget.inl:57
#3  0x0000000000742220 in ponder::detail::UserPropertyImpl<ponder::detail::Accessor2<Project, ponder::detail::FunctionTraits<std::string (Project::*)() const, void> > >::UserPropertyImpl (this=0x7fffc5dbcb00, name=..., accessor=...)
    at include/ponder/detail/userpropertyimpl.inl:64
#4  0x0000000000741f27 in ponder::detail::PropertyFactory2<Project, std::string (Project::*)() const, void (Project::*)(std::string const&), void>::create (
    name=..., accessor1=
    (void (Project::*)(std::string *, const Project *)) 0x59eefc <Project::getname() const>, accessor2=
    (void (Project::*)(Project *, const std::string &)) 0x59ef30 <Project::setname(std::string const&)>)
    at include/ponder/detail/propertyfactory.hpp:392
#5  0x000000000071d94b in ponder::ClassBuilder<Project>::property<std::string (Project::*)() const, void (Project::*)(std::string const&)> (
    this=0x7fff8a7dc4c0, name=..., accessor1=
    (void (Project::*)(std::string *, const Project *)) 0x59eefc <Project::getname() const>, accessor2=
    (void (Project::*)(Project *, const std::string &)) 0x59ef30 <Project::setname(std::string const&)>)
    include/ponder/classbuilder.inl:106

(gdb) fr 2
#2  0x00000000005258cc in ponder::classByType<std::string> ()
    at /ade/shhuang_exac/oracle/oss/thirdparty/ponder/include/ponder/classget.inl:57
57          return detail::ClassManager::instance().getById(detail::typeId<T>());

(gdb) fr 1
#1  0x00007ffff290ad9f in ponder::detail::ClassManager::getById (
    this=0x7ffff2b43900 <ponder::detail::ClassManager::instance()::cm>, id=...)
    at /scratch/backup/ponder/src/classmanager.cpp:99
99              PONDER_ERROR(ClassNotFound(id));

Does anyone know what was going on here? The call was called by ponder implicitly. I added the following line in the example program simple.cpp and it threw the same runtime exception.

const ponder::Class& metaclass2 = ponder::classByType<std::string>();

simple.cpp's Person class also has a std::string property but it runs fine. What have I missed?

Thanks,

We consider building a generic data repository (GDR) in which entries are stored in the following manner:

struct Entry {
    const ponder::Class& metaClass;
    void* p;
}

If we have created some object of class T (with T being a class declared to ponder)

T* pObject = ...

we would store it in the GDR like this:

someEntry.p = pObject;
someEntry.metaClass = ponder::classByObject(*pObject);

If that would work we could examine our GDR in a very generic way by initializing a ponder::UserObject for each entry and working with that ponder::UserObject through the reflection capabilities of ponder.

Alas, for such a generic data repository to work some obstacles would have to be overcome.

First of all, there currently is no functionality to initialize a ponder::UserObject from a ponder::Class and a void* pointer. (I'd guess this would be doable.)

Second, we would also like to store PODs, std::string, std::array, std::vector and the like in the GDR. For those types, there is no direct support in ponder, i.e. it is not possible to simply declare those types to ponder and initialize a ponder::UserObject for it. One way would be to wrap those types into custom classes like

template <typename T>
struct PodWrapper
{
    T value;
};
PONDER_TYPE(PodWrapper<uint8_t>)
PONDER_TYPE(PodWrapper<uint16_t>)
...
ponder::Class::declare<PodWrapper<uint8_t>>("PodWrapper<uint8_t>")
    .constructor()
    .property("Value", &PodWrapper<uint8_t>::value);
ponder::Class::declare<PodWrapper<uint16_t>>("PodWrapper<uint16_t>")
    .constructor()
    .property("Value", &PodWrapper<uint16_t>::value);
...    

but maybe there is some better way.

I would be glad to hear your opinion on the subject of this issue.

Debug build.

c:\program files (x86)\microsoft visual studio 14.0\vc\include\type_traits(1416): fatal error C1001: An internal error has occurred in the compiler.
1>  (compiler file 'f:\dd\vctools\compiler\utc\src\p2\main.c', line 246)
1>   To work around this problem, try simplifying or changing the program near the locations listed above.
1>  Please choose the Technical Support command on the Visual C++
1>   Help menu, or open the Technical Support help file for more information

apparently related to:

template<class _Callable,
    class... _Types> inline
    auto invoke(_Callable&& _Obj, _Types&&... _Args)
    -> decltype(_Invoker<_Callable, _Types...>::_Call(
        _STD forward<_Callable>(_Obj), _STD forward<_Types>(_Args)...))
    {   // INVOKE a callable object
    return (_Invoker<_Callable, _Types...>::_Call(
        _STD forward<_Callable>(_Obj), _STD forward<_Types>(_Args)...));
    }

in <type_traits>.

Hey, I compiled ponder with MSVC2015 (generated project using the CMAKE file provided).

In my project I set up the usual library linking paths and included ponder.lib and followed the code from the example code provided but I am getting unresolved external symbols (crazy big errors from VS). I'm fairly certain I have linked correctly (checked this over and over) but it doesn't seem to be linking.

Could this be a build issue?

Image of the errors: https://gyazo.com/29f2253c683a50b704c388afaa6b972d

Class header file: https://gyazo.com/95f69c5bce8fce24b45d11f9622b568c Class source file: https://gyazo.com/a591b22d2312e1936b81f4d40257a40e Main : https://gyazo.com/c9b11549ce0de44a72dc77f79ab9c53e

I've tried various things even included all the headers into my project incase their was some inline methods that were needed but still couldn't get it work.

Really want to use this library, I have been looking for a few days for a nice c++ reflection library and this seems perfect for my needs :)

Hello, I'm a member of Microsoft VCPKG, when I built this port in an internal version of Visual Studio, it failed with following errors: include\xstring(430): error C2027: use of undefined type 'std::basic_ostream<char,std::char_traits>' include\xstring(430): error C2065: 'iostate': undeclared identifier

This issue due to a change in MSVC: <string> doesn't transitively include<ostream>. For fixing this issue, we need to add #include<ostream> into the source.

Because there are multiple .cpp files that fail to compile due to this problem, in order to reduce the amount of modification, I hope to add modifications to a common header file, such as config.hpp.

Could you please help me confirm if it is appropriate to modify in config.hpp?

Suppose I define a object type as follows.

typedef struct myObj
{
  int a;
  int b;
} myObj;
PONDER_TYPE(myObj)

And use it for a property type of the Person class in simple.cpp.

class Person
{
public:
  myObj getObj() const { return m_obj; }
  void setObj(const myObj& obj) { m_obj = obj; }
...
private:
  myObj m_obj;
...
}

Register it.

   ponder::Class::declare<myObj>("myObj");
   ponder::Class::declare<Person>("Person")
        .constructor<std::string>()
        .property("obj", &Person::getObj, &Person::setObj)
...

Testing it as below.

    myObj obj;
    obj.a = 2;
    obj.b = 5;
    person.set("obj", obj);
    myObj retObj = person.get("obj").to<myObj>();
    std::cout << "a = " << retObj.a << " b = " << retObj.b << std::endl;

I expected retObj = obj but the output is: a = -10368 b = 32767

Dear developers,

We were using Ponder in version 2.0 which is not available anymore on the GitHub project page. Is there a reason for removing this version? The blog states that version 2.1 is the latest. Where can I find these versions?

Thanks in advance, Jupp

If I take the code of this file : https://github.com/billyquith/ponder/blob/master/test/ponder/arrayproperty.cpp

And I modify bool bools[2]; to bool bools[3]; And try to build using Visual Studio 2015 in x86 Debug

I get this error :

1>c:\program files (x86)\microsoft visual studio 14.0\vc\include\type_traits(1443): fatal error C1001: An internal error has occurred in the compiler.
1>  (compiler file 'f:\dd\vctools\compiler\utc\src\p2\main.c', line 255)
1>   To work around this problem, try simplifying or changing the program near the locations listed above.
1>  Please choose the Technical Support command on the Visual C++
1>   Help menu, or open the Technical Support help file for more information

Is there a way to use arrays larger than 2 apart from using std::array ?

Hi,

I am getting multiple defined symbol errors like so

obj/Debug/Sandbox/Mathf.conf.o: In function ponder::runtime::ObjectFactory::construct(ponder::Args const&, void*) const: Mathf.conf.cpp:(.text+0x168): multiple definition of ponder::runtime::ObjectFactory::construct(ponder::Args const&, void*) const obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x1a2): first defined here

I can successfully compile and run when I use ponder to build one of these classes (say Mathf) but as soon as I introduce another class (Vector2f) I get the above error. I understand why the error would be caused after quite a lot of digging about but I can't figure out why it is happening in this case.

My set up is as follows:

Mathf.h

#pragma once

class Mathf
{
public:
    static void Initialize();

    void MyFunction();
};

Mathf.cpp

#include "Mathf.h"

void Mathf::MyFunction()
{
    int i = 0;
}

Mathf.conf.cpp

#include "Mathf.h"

#include "Core/LuaState.h"
#include <ponder/classbuilder.hpp>
#include <ponder/uses/lua.hpp>  

PONDER_TYPE(Mathf);

void Mathf::Initialize()
{
    ponder::Class::declare<Mathf>()
		.function("MyFunction", &Mathf::MyFunction)
		;

	ponder::lua::expose<Mathf>(LuaState::L, "Mathf");
}

Vector2f.h, Vector2f.cpp & Vector2f.conf.cpp uses the exact same set up as described above so I won't write out that code as well...

I have tried linking to ponder both statically and dynamically and tested on Windows, Mac and Linux (Ubuntu) but I am still getting the same error.

Any ideas why this is happening? I've been trying to overcome this issue for 3 days now but have had no luck :(

Here is the full output from the compiler error:

obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::runtime::ObjectFactory::construct(ponder::Args const&, void*) const':
Mathf.conf.cpp:(.text+0x168): multiple definition of `ponder::runtime::ObjectFactory::construct(ponder::Args const&, void*) const'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x1a2): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::runtime::ObjectFactory::destroy(ponder::UserObject const&) const':
Mathf.conf.cpp:(.text+0x24a): multiple definition of `ponder::runtime::ObjectFactory::destroy(ponder::UserObject const&) const'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x284): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::runtime::ObjectFactory::destruct(ponder::UserObject const&) const':
Mathf.conf.cpp:(.text+0x28e): multiple definition of `ponder::runtime::ObjectFactory::destruct(ponder::UserObject const&) const'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x2c8): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::runtime::ObjectCaller::ObjectCaller(ponder::Function const&)':
Mathf.conf.cpp:(.text+0x2d2): multiple definition of `ponder::runtime::ObjectCaller::ObjectCaller(ponder::Function const&)'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x30c): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::runtime::ObjectCaller::ObjectCaller(ponder::Function const&)':
Mathf.conf.cpp:(.text+0x2d2): multiple definition of `ponder::runtime::ObjectCaller::ObjectCaller(ponder::Function const&)'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x30c): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::runtime::FunctionCaller::FunctionCaller(ponder::Function const&)':
Mathf.conf.cpp:(.text+0x312): multiple definition of `ponder::runtime::FunctionCaller::FunctionCaller(ponder::Function const&)'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x34c): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::runtime::FunctionCaller::FunctionCaller(ponder::Function const&)':
Mathf.conf.cpp:(.text+0x312): multiple definition of `ponder::runtime::FunctionCaller::FunctionCaller(ponder::Function const&)'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x34c): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder_ext::pushUserObject(lua_State*, ponder::UserObject const&)':
Mathf.conf.cpp:(.text+0x352): multiple definition of `ponder_ext::pushUserObject(lua_State*, ponder::UserObject const&)'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x38c): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::lua::expose(lua_State*, ponder::Class const&, ponder::detail::basic_string_view<char, std::char_traits<char> >)':
Mathf.conf.cpp:(.text+0x1423): multiple definition of `ponder::lua::expose(lua_State*, ponder::Class const&, ponder::detail::basic_string_view<char, std::char_traits<char> >)'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x145d): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::lua::expose(lua_State*, ponder::Enum const&, ponder::detail::basic_string_view<char, std::char_traits<char> >)':
Mathf.conf.cpp:(.text+0x168c): multiple definition of `ponder::lua::expose(lua_State*, ponder::Enum const&, ponder::detail::basic_string_view<char, std::char_traits<char> >)'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x16c6): first defined here
obj/Debug/Sandbox/Mathf.conf.o: In function `ponder::lua::runString(lua_State*, char const*)':
Mathf.conf.cpp:(.text+0x17f0): multiple definition of `ponder::lua::runString(lua_State*, char const*)'
obj/Debug/Sandbox/Vector2.conf.o:Vector2.conf.cpp:(.text+0x182a): first defined here
collect2: error: ld returned 1 exit status
Sandbox.make:98: recipe for target '../Bin/Debug/libSandbox.so' failed
make[1]: *** [../Bin/Debug/libSandbox.so] Error 1
Makefile:28: recipe for target 'Sandbox' failed
make: *** [Sandbox] Error 2

If a class, whose registration is achieved by PONDER_AUTO_TYPE, is not registered when it is referenced using classByName, then a ClassNotFound exception is thrown.

Hi, thank you for your continued efforts on this project.

There is a subfolder include/ponder-xml but as far as I can tell these features are not included in the documentation.

Actually, the methods serializeand deserialize (with the RapidXML compatibility layer) appear to do exactly what I need, but it would be even better if there was a RapidJSON alternative!

Do you think it would be possible to:

1. Include the serialization methods in the documentation.
2. Provide a small round-trip example.
3. Consider an enhancement to also provide a [Rapid]JSON compatibility layer.

Compiler GCC version：gcc (GCC) 11.2.0 In this version compiler, cause std::logic_error type not found error, add header file include to fix this compile error.

Hi,

I am trying to use ponder for reflection. I create instances of a class declared to ponder and then store the pointer to the objects in a generic datamodel.

The code looks something like below:

bool object_factory()
{  
  const ponder::Class& metaClass = ponder::ClassByType<Type>();
  ponder::UserObject object = ponder::runtime::create(metaClass);
  void* ptr = object.pointer();
  if(add_to_datamodel(ptr) == FAILURE)
  {
    ponder::runtime::destroy(object);
    return FAILURE;
  }
  return SUCCESS;
}

The code builds fine and I see below runtime error when I execute unit test where the add_to_datamodel failed. The object destroy is leading to an invalid pointer.

free(): invalid pointer
Aborted

I run google tests on ubuntu 20.04 version.

I tried to maintain object creation and destruction similar to the library examples and it doesn't work, could you help me with the issue?

class Person
{
public:
     // constructor
    Person(const std::string& name)
        : m_name(name)
    {}
 
    // accessors for private members
    std::string name() const { return m_name; }
    void setName(const std::string& name) { m_name = name; }
 
    // public members
    float height;
    unsigned int shoeSize;
 
    // member function
    bool hasBigFeet() const { return shoeSize > 10; } // U.K.!
 
private:
    std::string m_name;
};
PONDER_TYPE(Person)     // declare the type to Ponder
 
static void declare()   // declare the class members to Ponder
{
    ponder::Class::declare<Person>("Person")
        .constructor<std::string>()
        .property("name", &Person::name, &Person::setName)
        .property("height", &Person::height)
        .property("shoeSize", &Person::shoeSize)
        .function("hasBigFeet", &Person::hasBigFeet)
        ;
}
int main(){
    declare();
    const ponder::Class& metaclass = ponder::classByType<Person>();
    ponder::UserObject data = ponder::runtime::create(metaclass, "Tom");
    //auto value = data.get("m_value");
    //std::cout << value << std::endl;   
    //data.set("m_value", 1000);
    return 0;
}

I compiled the demo code but got the following error: undefined reference to `ponder::runtime::ObjectFactory::construct(ponder::Args const&, void*) const'

Users would prefer not to have to use exceptions (see #53). Use "tryGet" mechanism to get values instead of throwing exceptions. Exceptions are inefficient and wrapping them is tedious. Also some applications (like games) don't want to use exceptions at all.

I'm upgrading my project to the latest version of ponder and in the release notes I saw "Changed UserObject reference semantics.". With this change I'm not sure how I go about setting nested user types. For example if you look at seralise.hpp ArchiveReader::read

if (arrayProperty.elementType() == ValueKind::User) { read(item, arrayProperty.get(object, index).to<UserObject>()); } With the new semantics, doesn't that Value.to just make a copy and not actually update the object as you'd expect?

If I'm way off and there's documentation you could point me at it would be greatly appreciated.

Thanks