Hi,
What's the purpose of having assert, require and ensure, when they
all do the same thing?
I know a rose by any name would be just as sweet, but by three names
it wouldn't be three times sweeter....
-P.
On 21 Apr 1999, Phil Austin wrote:
> The following message is a courtesy copy of an article
> that has been posted as well.
>
>
> In case anyone else is interested in doing rudimentary "design by
> contract" in Fortran, here is a simple subroutine that works for me
> using Solaris Fortran 2.0 using the fortran preprocessor fpp. I'd be
> interested in hearing about improvements and portability.
>
> For those who aren't familiar with C-style assertions, they are
> enormously useful macro statements that test the truth of a logical
> condition. If the condition isn't met, then the program halts and
> prints the line number. If the program is compiled with -DNDEBUG,
> then the assertions are no-ops that are optimized away.
>
> Here's an example of a precondtion test:
>
> --------testit.F90
>
> #include "assert.h"
>
> program test_assert
> implicit none
> real a,b,c
> b=4.
> a=5.
> c=8.
> REQUIRE(a .lt. b)
> end program test_assert
>
> when compiled (without -DNDEBUG) and run, the resulting output is:
>
> <peacock /nfs/peacock/local1/datatmp/phil/testf90.dir> testit
> Precondition (a .lt. b) failed in file testit.F90 line 0009
>
> Two files are needed to get this to work on Solaris:
>
> ----------assert.h
>
> #ifdef NDEBUG
> #define assert(EX)
> #define REQUIRE(EX)
> #define ENSURE(EX)
> #else
> #define assert(EX) if(.not. ( EX )) call FortranAssert('Assertion',#EX, __FILE__, __LINE__)
> #define REQUIRE(EX) if(.not. ( EX )) call FortranAssert('Precondition',#EX, __FILE__, __LINE__)
> #define ENSURE(EX) if(.not. ( EX )) call FortranAssert('Postcondition',#EX, __FILE__, __LINE__)
> #endif
>
> and:
>
> _________ FortranAssert.f90
>
> subroutine FortranAssert(prepost,expression,filename,linenum)
> character(*), intent(in) :: prepost,expression, filename
> integer, intent(in) :: linenum
> write(6,'(a,a,a,a,a,a,i4.4)') prepost," (", expression, ") failed in file ", filename," line ",linenum
> stop
> end subroutine FortranAssert
>
>
> --
> ------------------------------------------------------------
> Phil Austin ([log in to unmask])
> Department of Geography, Tel: (604) 822-2663
> University of British Columbia, B.C. Fax: (604) 822-6150
>
--
********* Peter S. Shenkin; Schrodinger, Inc.; (201)433-2014 x111 *********
*********** [log in to unmask]; http://www.schrodinger.com ***********
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