Re: pre-processor macro associated with availability of execute_command_line

[Tim Prince <n8tm at aol dot com>]

On 1/2/2012 1:15 PM, Tobias Burnus wrote:
> Tim Prince wrote:
> > As execute_command_line has been available in gfortran for over a year
> > without penetrating to commonly used targets (e.g. mingw-64), I
> > wondered if there is a suggestion for pre-processor macro to choose a
> > source code branch, such as keying on gcc version number.
> > I suppose if it were easy to back-port to gfortran 4.5, it would have
> > been done already.
>
> GCC 4.7.0 (including "gfortran -cpp" and "cpp") set (cf. "gfortran -cpp
> -dM test.F90"):
> #define __GNUC__ 4
> #define __GNUC_MINOR__ 7
>
> The main reason that execute_command_line has not been backported to
> older GCC versions is that it is not a regression and not a bug. (The
> patch is not very small but rather localized.) Actually, I am surprised
> that you are considering a backport: execute_command_line is a Fortran
> 2008 feature and very few compilers support it. On the other hand, the
> vendor intrinsic SYSTEM (either as function or as subroutine - or as
> with gfortran: both) is widely supported. (Besides the standard
> conformance, the main advantage of execute_command_line is the support
> of WAIT=.false., which is often not needed.)
>
> Tobias
Thanks, I was a bit concerned about lack of assurances about system() 
for various targets, although it clearly works for mingw gfortran:

#if !defined __GFORTRAN__ || __GNUC__ < 4 || __GNUC_ == 4 && GNUC_MINOR < 6
      junk=system("uname -ps > uname.txt")
#else
      call execute_command_line("uname -ps > uname.txt")
#endif


--
Tim Prince