# Problem when passing a VALUE as parameter

**URL:** <https://www.ruby-forum.com/t/problem-when-passing-a-value-as-parameter/129915>\
**Category:** Ruby\
**Created:** [February 22, 2008, 5:30pm UTC](https://www.ruby-forum.com/t/problem-when-passing-a-value-as-parameter/129915 "2008-02-22T17:30:32Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![mag](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/58f4c7/32.png) [@mag](https://www.ruby-forum.com/u/mag)\
**Post date:** [February 22, 2008, 5:30pm UTC](https://www.ruby-forum.com/t/problem-when-passing-a-value-as-parameter/129915/1 "2008-02-22T17:30:32Z")

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Hi,

I’m new to Ruby and I’m currently working on embedding Ruby-VTK within  
C++.  
Ruby-Vtk is a patch to add on VTK (Visualization ToolKit) to use from  
Ruby.  
I want to get a pointer from an VALUE object with the method  
vtkRubyGetPointerFromObject(VALUE) which is declared in the  
vtkRubyUtil.h file.  
My problem is that when I pass a VALUE to this method, the compiler  
tells me that there’s an undefined reference to  
vtkRubyGetPointerFromObject(unsigned long).  
I know that in the ruby.h header file VALUE is declared as an unsigned  
long, but I don’t know why it converts the VALUE object during the  
compilation.

Do you have any idea why I’ve got this problem ?

Thanks in advance for your answers.

Mag