fypp 0.11

Main features

• Definition and evaluation of preprocessor variables:

  #:if DEBUG > 0
    print *, "Some debug information"
  #:endif
  
  #:setvar LOGLEVEL 2

• Macro defintions and macro calls (apart of minor syntax differences similar to scoped intelligent Fortran macros, which probably will be once part of the Fortran standard):

  #:def assertTrue(cond)
  if (.not. ${cond}$) then
    print *, "Assert failed in file ${_FILE_}$, line ${_LINE_}$"
    error stop
  end if
  #:enddef
  
  $:assertTrue('size(myArray) > 0')

• Conditional output:

  program test
  #:if defined('WITH_MPI')
    use mpi
  #:elif defined('WITH_OPENMP')
    use openmp
  #:else
    use serial
  #:endif

• Iterated output:

  interface myfunc
  #:for dtype in [ 'real', 'dreal', 'complex', 'dcomplex' ]
    module procedure myfunc_${dtype}$
  #:endfor
  end interface myfunc

• Inline directives:

  logical, parameter :: hasMpi = #{if defined('MPI')}#.true.#{else}#.false.#{endif}#

• Insertion of arbitrary Python eval-expressions:

  character(*), parameter :: comp_date = "${time.strftime('%Y-%m-%d')}$"

• Inclusion of files during preprocessing:

  #:include "macrodefs.fypp"

• Using Fortran-style continutation lines in preprocessor directives:

  #:if var1 > var2 &
      & or var2 > var4
    print *, "Doing something here"
  #:endif

• Passing multiline arguments to macros:

  #:def debug_code(code)
    #:if DEBUG > 0
      $:code
    #:endif
  #:enddef
  
  #:call debug_code
    if (size(array) > 100) then
      print *, "DEBUG: spuriously large array"
    end if
  #:endcall

• Preprocessor comments:

  #! This will not show up in the output
  #! Also the newline characters at the end of the lines will be suppressed

• Suppressing the preprocessor output in selected regions:

  #! Definitions are read, but no output (e.g. newlines) will be produced
  #:mute
  #:include "macrodefs.fypp"
  #:endmute

Installing

Fypp needs a working Python interpreter either with version 2.7 or with version 3.2 or above.

The command line tool is a single stand-alone script. You can run it directly from the source folder

FYPP_SOURCE_FOLDER/bin/fypp

or after copying it from the bin folder to any location listed in your PATH environment variable, by just issuing

fypp

Alternatively, you can use Pythons installer (pip) to install Fypp on your system:

pip install fypp

This installs the command line tool fypp as well as the Python module fypp. Latter you can import if you want to access the functionality of Fypp directly from within your Python scripts.

Running

The Fypp command line tool reads a file, preprocesses it and writes it to another file, so you would typically invoke it like:

fypp source.fypp source.f90

which would process source.fypp and write the result to source.f90. If input and output files are not specified, information is read from stdin and written to stdout.

The behavior of Fypp can be influenced with various command line options. A summary of all command line options can be obtained by:

fypp -h