Re: A question about the declaration of mxCreateStructArray in mex.

[David Bateman]

Aquil H. Abdullah wrote:
> First let me  say that I know that Octave is not Matlab so this post
> is mostly for clarity, (Although
>
> Matlab declares the function mxCreateStructArray as follows:
>
> mxArray *mxCreateStructArray(mwSize ndim, const mwSize *dims, int
> nfields,
>                                                const char **fieldnames);
>
> Octave defines the function mxCreateStructArray as follows:
>
> mxArray *
> mxCreateStructArray (int ndims, int *dims, int num_keys, const char
> **keys)
> {
>   return maybe_mark_array (new mxArray (ndims, dims, num_keys, keys));
> }
>
> While compiling a bit of mex code for use with octave I ran into the
> following error:
>
> Utils.cpp:38: error: invalid conversion from `const int*' to `int*'
> Utils.cpp:38: error:   initializing argument 2 of `mxArray*
> mxCreateStructArray(int, int*, int, const char**)'
>
> To fix this I used a conditionally compiled the code that I was
> working on:
>
> #ifdef USE_OCTAVE
>   mxArray * v = mxCreateStructArray(ndims, const_cast <int *>(dims),
> nFields, fields);
> #else
>   mxArray * v = mxCreateStructArray(ndims, dims, nFields, fields);
> #endif
>
> Since a call to mxCreateStructArray eventually winds up in mxArray,
> which supplies a the constructor:
>
> mxArray (int ndims, const int *dims, int num_keys, const char **keys);
>
> I was wondering if there was a particular reason that
> mxCreateStructArray was implemented in its current fashion?
>
> Thanks!
Hi Aquil,

I think the reason *dims is not declared const here is purely an
oversight, and the const should just be added.. Patch attached against
the CVS.

David

-- 
David Bateman                                address@hidden
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*** ./src/mex.cc.orig50 2007-07-20 10:06:42.018433444 +0200
--- ./src/mex.cc        2007-07-20 10:07:40.425295509 +0200
***************
*** 2495,2501 ****
  }
  
  mxArray *
! mxCreateStructArray (mwSize ndims, mwSize *dims, int num_keys, const char 
**keys)
  {
    return maybe_mark_array (new mxArray (ndims, dims, num_keys, keys));
  }
--- 2495,2501 ----
  }
  
  mxArray *
! mxCreateStructArray (mwSize ndims, const mwSize *dims, int num_keys, const 
char **keys)
  {
    return maybe_mark_array (new mxArray (ndims, dims, num_keys, keys));
  }
*** ./src/mexproto.h.orig50     2007-07-20 10:06:35.977756987 +0200
--- ./src/mexproto.h    2007-07-20 10:06:56.055680837 +0200
***************
*** 123,129 ****
  extern OCTINTERP_API mxArray *mxCreateSparse (mwSize m, mwSize n, mwSize 
nzmax, mxComplexity flag);
  extern OCTINTERP_API mxArray *mxCreateSparseLogicalMatrix (mwSize m, mwSize 
n, mwSize nzmax);
  extern OCTINTERP_API mxArray *mxCreateString (const char *str);
! extern OCTINTERP_API mxArray *mxCreateStructArray (mwSize ndims, mwSize 
*dims, int num_keys, const char **keys);
  extern OCTINTERP_API mxArray *mxCreateStructMatrix (mwSize rows, mwSize cols, 
int num_keys, const char **keys);
  
  // Copy constructor.
--- 123,129 ----
  extern OCTINTERP_API mxArray *mxCreateSparse (mwSize m, mwSize n, mwSize 
nzmax, mxComplexity flag);
  extern OCTINTERP_API mxArray *mxCreateSparseLogicalMatrix (mwSize m, mwSize 
n, mwSize nzmax);
  extern OCTINTERP_API mxArray *mxCreateString (const char *str);
! extern OCTINTERP_API mxArray *mxCreateStructArray (mwSize ndims, const mwSize 
*dims, int num_keys, const char **keys);
  extern OCTINTERP_API mxArray *mxCreateStructMatrix (mwSize rows, mwSize cols, 
int num_keys, const char **keys);
  
  // Copy constructor.

2007-07-20  Aquil H. Abdullah <address@hidden>

        * mex.cc (mxCreateStructArray): Declare second arg as const
        * mexproto.h (mxCreateStructArray): Ditto.