[R] DLL's

[Guido Masarotto]

On Tue, Feb 23, 1999 at 09:45:21PM +0100, james.pigott at ucd.ie wrote:
> I'm using Borland C++ for windows version 4.51 to export functions 
> in a dll to R but i've encountered the following problems
> --  R crashes when function has more than one parameter
> --  Array subscripts in C++ code access wrong elements
> --  dll is not portable to different computer .i.e R (dyn.load) will only  
>     call the dll on the the machine the dll was compiled o
  Both B. Ripley and I are 
  making available DLL's which don't seem to suffer of your
  first and third problem. However, none of these, if
  I remember,  has C++ code.
  Crashes are easy to obtain if you don't respect exactly
  the ".C calling convention", e.g., if your function think
  to receive a string and not a vector of strings. This
  could also explain second problem. But it is just an 
  hypothesis. If you want, try to reduce at the minimum
  your source (at the level of a small toy) then post it.

> 
> Does the dll need to be compiled on a particular version of C ??
  In theory no. I have used dll's compiled with Visual C++ without
  problems. And I received some reports that lcc works well.
  However, most of the people are using the GNU copyleft
  egcs compiler. Surely, binaries at CRAN are made using 
  egcs.

> 
> I would appreciate the solution to these problem(s)  and/or perhaps 
> an example of some C code.

  A basic example of dynamic loading (including call_[R,S]) is
  in  the demo/dynload directory of the source. Observe that
  the C dll calls routines in the main code which under 
  Windows is in R.dll. Hence, you need to link against
  R.dll (how depends upon the compiler, you have to
  generate an appropriate import library from the R.dll,
  on this point,   not specific to R but including examples of use of many
  different compilers, you can give a look to the Luke Tierney's
  http://stat.umn.edu/~luke/xls/projects/dlbasics/dlbasics.html
  

  guido 
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