topic Re: C++ objects in Fortran77 in Operating System - OpenVMS

C++ objects in Fortran77

Paul Vinders — Mon, 11 Sep 2006 03:42:40 GMT

Hi everybody,

does anyone know how to use a C++ class in Fortran77? And how to call C++ methods in Fortran77?

Sincerely,
Paul Vinders

Re: C++ objects in Fortran77

Robert Gezelter — Mon, 11 Sep 2006 04:19:02 GMT

Paul,

One way (which I implemented for a client product) is to write a C-calling convention set of binding routines.

How easy this is depends on what precisely the interface specification is.

- Bob Gezelter

Re: C++ objects in Fortran77

John Gillings — Mon, 11 Sep 2006 21:12:51 GMT

Paul,

Generic answer... on OpenVMS any language can call routines written in any other language. You just need to make sure the arguments match in position, data type and passing mechanism. For complex data types, there may be compatibility issues between languages, so it's best to keep interfaces as simple as possible. You may also have to force specific mechanisms using FORTRAN built-in functions %VAL, %REF & %DESCR

For C++ you have the added complication of name mangling - compiler generated names to keep them unique and fit within the name length limits of the OpenVMS linker. You can specify a C++ global entity has a non-mangled name, or, as Bob suggests, write a jacket interface with non-mangled names.

If you're really keen, you can determine the mangled names from the librarian, linker map or mangler/demangler utilities and call them directly, but the Fortran side will be rather cryptic!