PreForM Preprocessing

FoBiS.py integrates seamlessly with PreForM.py, a powerful yet simple preprocessor designed for Fortran. PreForM.py provides template expansion and cpp-compatible preprocessing, making it easy to generate repetitive Fortran code.

Basic usage

Activate preprocessing with -preprocessor (or the legacy -pfm/--preform alias):

FoBiS.py build -preprocessor

By default, PreForM.py is invoked as the preprocessor. Each source file is passed through PreForM.py before compilation. The intermediate preprocessed files are deleted immediately after compilation.

To use a different preprocessor, specify its command:

FoBiS.py build -preprocessor my_preprocessor

Keeping preprocessed files

To retain the preprocessed sources (useful for debugging or distribution), specify an output directory with -dpp/--preprocessor_dir:

FoBiS.py build -preprocessor -dpp ./preprocessed/

The directory is relative to the build path, similar to obj/ and mod/.

Preprocessing only selected files

To preprocess only files with certain extensions (rather than all sources), use -epp/--preprocessor_ext:

FoBiS.py build -preprocessor -dpp ./preprocessed/ -epp .F90 .F95 .F03

Only files ending in .F90, .F95, or .F03 are passed through PreForM.py; all other files are compiled directly.

Preprocessor arguments

Pass extra flags to the preprocessor command with -app/--preprocessor_args:

FoBiS.py build -preprocessor -app "-DDEBUG=1"

Compiler-level preprocessor flags (e.g. -DFEATURE) go to -p/--preproc:

FoBiS.py build -preprocessor -p "-DUSE_MPI"

To suppress the -o output flag in the preprocessor invocation:

FoBiS.py build -preprocessor -npp

fobos options

[gnu-preform]
compiler        = gnu
cflags          = -c -O2
preprocessor    = PreForM.py
preprocessor_dir = ./pfm/
preprocessor_ext = .pfm .F90 .F03
preprocessor_args = -DDEBUG
src             = ./src/
build_dir       = ./build/
target          = main.f90
output          = myapp

Preprocessor option reference

Option	Description
-preprocessor [CMD]	Enable preprocessing; optional custom command (default: PreForM.py)
-p, --preproc	Preprocessor flags for the main compiler
-app, --preprocessor_args	Flags passed to the preprocessor
-npp, --preprocessor_no_o	Omit -o from the preprocessor command
-dpp, --preprocessor_dir	Directory for preprocessed sources (kept if set)
-epp, --preprocessor_ext	Extensions of files to preprocess

Example workflow

Given a source tree using .pfm extension for template files:

src/
├── main.f90
└── templates/
    ├── vector.pfm
    └── matrix.pfm

FoBiS.py build \
  -preprocessor \
  -dpp ./preprocessed/ \
  -epp .pfm \
  -cflags "-c -O2" \
  -src ./src/

FoBiS.py expands vector.pfm and matrix.pfm through PreForM.py, saves the results in ./preprocessed/, then compiles everything together.