Re: [luabind] How to get the attributes of a lua class, without their names, using luabind

[Pavel K. <pa...@ya...>]

This example works for me (but I use another fork: 
https://github.com/decimad/luabind-deboostified)

lua code:

   local obj = {}
   obj.foo = function (self)
       puts("obj:foo")
   end
   obj.data = 42

   dump_object(obj)

cpp code:

   void dump_object(const luabind::object &obj)
   {
       for (luabind::iterator it(obj), end; it!=end; it++)
       {
           auto s = object_cast<std::string>(it.key());
           puts(s.c_str());
       }
   }

What kind of lua object are you trying to iterate over?
On 12/12/2015 0:23 AM, jean-baptiste griffo wrote:
> Hi,
>
> Well it's weird but I don't remember the exact fork I'm using, I think I
> use this one
> https://github.com/mrsharpoblunto/LHP/tree/master/luabind-0.7/include/luabind
> I do not use the official release because I had some problems related to
> size_t & x64 builds, and this fork solved it.
>
> Here is the c++ code, please note that at this point I'm 100% sure the
> object on the stack is the "self" of my class instance
>
> //get the luabind object from the stack
> luabind::object o(luabind::from_stack(L, lastIndex));
>
> for (luabind::iterator i(o), end; i != end; ++i)
> {
>      try
>      {
>          std::string strKey = luabind::object_cast<std::string>(i.key());
>          printf("%s\n",strKey.c_str());
>      }
>      catch(luabind::cast_failed & e)
>      {
>          printf("error\n");
>      }
> }
>
> ----------
>
> As a result, it simply prints "error" indefinitely.
>
> Thanks.
>
>
> On 11/12/2015 17:57, Pavel Kovalenko wrote:
>> Hi,
>>
>> I don't have such problem (using luabind-deboostified fork). Could you
>> show the code which causes an infinite loop? Which fork do you use?
>>
>> On 12/11/2015 3:00 PM, luabind-user-request@... wrote:
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>>> Today's Topics:
>>>
>>>      1. Re: How to get the attributes of a lua class without their
>>>         names, using luabind (Crashy)
>>>
>>>
>>> ----------------------------------------------------------------------
>>>
>>> Message: 1
>>> Date: Thu, 10 Dec 2015 05:07:38 -0700 (MST)
>>> From: Crashy <jean-baptiste.griffo@...>
>>> Subject: Re: [luabind] How to get the attributes of a lua class
>>> 	without their names, using luabind
>>> To: luabind-user@...
>>> Message-ID: <1449749258848-7670726.post@...>
>>> Content-Type: text/plain; charset=us-ascii
>>>
>>> Hi !
>>>
>>> I hate to 'bump' very old topics, but I'm facing the same problem while
>>> writing a lua debugger.
>>> I can access values by name, but using the iterator results in an infinite
>>> loop.
>>> Iterators are doing well when the object is a simple table though, it only
>>> fails when the object is a luabind class.
>>>
>>> Does anybody has a solution to iterate over member variables of a luabind
>>> class ?
>>>
>>> Thanks !
>>>
>>>
>>> Thibault Ehrhart wrote
>>>> Hello everyone,
>>>>
>>>> I have a Lua class (defined using luabind's 'class' keyword) and I'd like
>>>> to get the value of the attributes defined in Lua, with C++.
>>>>
>>>> In the code below, I've defined a class, created an instance "foo" and set
>>>> a custom attribute "bar" to that instance. Finally, I am calling a C++
>>>> function which has to print the attributes of the instance passed as a
>>>> parameter.
>>>>
>>>> Here's the Lua code :
>>>>
>>>>       class 'MyLuaClass'
>>>>       function MyLuaClass:__init() end
>>>>
>>>>       foo = MyLuaClass()
>>>>       foo.bar = "baz";
>>>>       PrintAttributes(foo);
>>>>
>>>> And now the C++ code of the PrintAttributes function, obj is a class
>>>> instance:
>>>>
>>>>       void PrintAttributes(luabind::object &obj)
>>>>       {
>>>>           // Direct access works
>>>>           std::cout << obj["bar"] << std::endl; // Will print "baz" :-)
>>>>
>>>>           // But what if I don't know the name of the variable(s)?
>>>>           for (luabind::iterator it(obj); it != luabind::iterator(); ++it)
>>>>           {
>>>>               // Doesn't work since obj is an userdata
>>>>           }
>>>>       }
>>>>
>>>> I've also tried to use class_info but it only works with properties
>>>> defined
>>>> in a C++ class. Is there a way to access those defined with Lua?
>>>>
>>>> Regards,
>>>
>>>
>>>
>>>
>>> --
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>>>
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>

-- 
Best regards, Pavel Kovalenko.