Re: [boost] Re: Detachable objects in BPL

From: Phlip (pplumlee_at_[hidden])
Date: 2001-02-09 14:19:19

Proclaimed Greg Colvin from the mountaintops:

> What is NULL defined as on your system?  ((void*)0) ?

I see it's time for a version dump:

  LinuxPPC
  g++ 2.95.2

This line returns an error:

  char * a = (void*)0;

And these lines...

  #define DEBUG_(x) cout << WRAP(x) << endl
  #define WRAP(x) #x
  DEBUG_(NULL)

...return "__null".

This is an amusing chain of events, and I could look up g++'s '__null' for 
you, but I don't see how it's relevant. (Then again I had no idea one 
could do what Boost does with traits.)

Here's the function to make the goods. I made the names up to protect the 
guilty:

              static organ_ptr_t
      makeOrgan(char const * name)
              {
              if (name)
                      {
                      organ_ptr_t result (new organ);
                result -> m_strName = name;
                return result;
                }
        else
                return organ_ptr_t (NULL);
              }

The result eventually passes to Python, and that (after the line aOrgan == 
None) enlightens us with this:

    if aOrgan.getName() == "":  return
RuntimeError: Converting from python, pointer or smart pointer to <5organ> 
is NULL.

What's happening is this line fails to detect the NULL as a None:

    if aOrgan == None:  return

Then the next line bombs.

Right now I'm using a sentinel value instead of this NULL to mark a 
non-existent item, but I'd rather be able to use Python's built in None 
correctly.

-- 
  Phlip                          phlip_cpp_at_[hidden]
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