Re: Trouble binding a class - should be simple

You might also want to look at using the "property" mechanism to automate
use of set/get:

.property("x", &Object::getX, &Object::setX)

that way you can do
bla = Object()
bla.x = 5
print(bla.x)

Ryan

On Thu, May 5, 2011 at 9:17 AM, Simon Pickles <[email protected]> wrote:

>  On 05/05/2011 11:35, Tony Kostanjsek wrote:
>
> Have you tried to add a binding for the default constructor?
>
>
>
>
> On 05.05.2011, at 11:53, Simon Pickles <[email protected]> wrote:
>
>   On 05/05/2011 09:48, feng qiu wrote:
>
> Please try v*:*getX().
>
> On 5 May 2011 15:56, Simon Pickles <[email protected]> wrote:
>
>>
>> Hello,
>>
>> I am trying to expose part of the btVector3 class from BulletPhysics to
>> Lua:
>>
>> http://www.bulletphysics.com/Bullet/BulletFull/classbtVector3.html
>>
>> My first attempt:
>>
>> // C++
>>   void RegisterPhysicsTypesWithLua( lua_State* lua )
>>   {
>>     module( lua )
>>     [
>>       class_<btVector3>( "btVector3" )
>>       .def( "getX",&btVector3::getX )
>>       .def( "getY",&btVector3::getY )
>>       .def( "getZ",&btVector3::getZ )
>>       .def( "setX",&btVector3::setX )
>>       .def( "setY",&btVector3::setY )
>>       .def( "setZ",&btVector3::setZ )
>>     ];
>>   }
>>
>> --Lua
>> print("Testing btVector3 in lua")
>> v = btVector3()
>> print("btVector3 created")
>>
>> print( "x = " .. v.getX() )  -- should print x = 0.0
>> v.setX(99.9)
>> print( "x = " .. v.getX() )  -- should print x = 99.9
>>
>> ------------------------------------------
>> This first attempt produces the error:
>> "Attempt to call a nil value"
>>
>>
>> So I added a constructor and tried again:
>>
>> // C++
>>   void RegisterPhysicsTypesWithLua( lua_State* lua )
>>   {
>>     module( lua )
>>     [
>>       class_<btVector3>( "btVector3" )
>>       .def( constructor<  float, float, float>() )
>>       .def( "getX",&btVector3::getX )
>>       .def( "getY",&btVector3::getY )
>>       .def( "getZ",&btVector3::getZ )
>>       .def( "setX",&btVector3::setX )
>>       .def( "setY",&btVector3::setY )
>>       .def( "setZ",&btVector3::setZ )
>>     ];
>>   }
>>
>> --Lua
>> print("Testing btVector3 in lua")
>> v = btVector3(1.0,2.0,3.0)
>> print("btVector3 created")
>>
>> print( "x = " .. v.getX() )  -- should print x = 1.0
>> v.setX(99.9)
>> print( "x = " .. v.getX() )  -- should print x = 99.9
>>
>> ------------------------------------------
>> This second attempt produces the error:
>> "No such operator defined"
>>
>>
>> I have double checked that I am definately calling the
>> RegisterPhysicsTypesWithLua with the correct LuaState.
>>
>> I expected this to be reasonably trivial as I have been exposing my own
>> classes with ease. This is however, the first time I have tried to
>> expose a 3rd party class. Am I missing something obvious?
>>
>> Thanks very much
>>
>> Simon
>>
>   Well spotted (too used to Python!). The second version works!
>
> However doesn't explain why the first version (with default ctor) fails. It
> never gets to the getX() call:
> Testing btVector3 in lua
> Error: Attempt to call a nil value
>
>
> btVector3 does indeed have a default ctor:
>
> http://www.bulletphysics.com/Bullet/BulletFull/classbtVector3.html#a82b4c5da54ecd4c91bd9b056dea0d288
>
> Thanks
>
>
>  Thanks Tony, Didn't know I could do that.
>
> Is this a top-posting list then? ;)
>
>
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-- 
Ryan Pavlik
HCI Graduate Student
Virtual Reality Applications Center
Iowa State University

[email protected]
http://academic.cleardefinition.com
Internal VRAC/HCI Site: http://tinyurl.com/rpavlik

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The most intuitive, comprehensive, and cost-effective network 
management toolset available today.  Delivers lowest initial 
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