CODEWITHSUNDEEP
fortranscons
taerath
taerath

Reputation: 85

Scons: What is the purpose of `FORTRAN*` variables when building Fortran?

What is the purpose of the FORTRAN* variables in Scons? The manpage describes them as the default settings for all versions of Fortran. But as far as I can tell, in practice they are never used because the specific variables for the different Fortran dialects that always take precedence (F77*, F90*, F95*).

Is there a way to change the mapping from file extensions to Fortran dialects, so that some files get mapped to the default instead?

Upvotes: 4

Views: 137

Answers (1)

casey
casey

Reputation: 6915

Looking through the SCons source (particularly Tool/FortranCommon.py) it appears the that FORTRAN is treated as a dialect along with F77, F90, F95 and F03 rather than a parent to all of them. It looks like the FORTRAN variant of the variables will be used for source files named with .f, .for, .ftn, .fpp, and .FPP though they can be overridden from the variables FORTRANFILESUFFIXES and FORTRANPPFILESUFFIXES.

The code that sets this up is:

def add_fortran_to_env(env):
    """Add Builders and construction variables for Fortran to an Environment."""
    try:
        FortranSuffixes = env['FORTRANFILESUFFIXES']
    except KeyError:
        FortranSuffixes = ['.f', '.for', '.ftn']

    #print "Adding %s to fortran suffixes" % FortranSuffixes
    try:
        FortranPPSuffixes = env['FORTRANPPFILESUFFIXES']
    except KeyError:
        FortranPPSuffixes = ['.fpp', '.FPP']

    DialectAddToEnv(env, "FORTRAN", FortranSuffixes,
                    FortranPPSuffixes, support_module = 1)

where DialectAddToEnv gives values to the Fortran build variables, e.g (dialect is the second variable passed to to the function):

 env['%sCOM' % dialect]     = '$%s -o $TARGET -c $%sFLAGS $_%sINCFLAGS $_FORTRANMODFLAG $SOURCES' % (dialect, dialect, dialect)

The code that sets up F77, F90, F95, etc is very similar, e.g.:

def add_f90_to_env(env):
    """Add Builders and construction variables for f90 to an Environment."""
    try:
        F90Suffixes = env['F90FILESUFFIXES']
    except KeyError:
        F90Suffixes = ['.f90']

    #print "Adding %s to f90 suffixes" % F90Suffixes
    try:
        F90PPSuffixes = env['F90PPFILESUFFIXES']
    except KeyError:
        F90PPSuffixes = []

    DialectAddToEnv(env, "F90", F90Suffixes, F90PPSuffixes,
                    support_module = 1)

There is no mechanism to fall back from one dialect to FORTRAN. Each dialect (including FORTRAN) is separate and mapped from the file name endings, which are configurable.

Upvotes: 4

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