Welcome to fclap’s documentation!#

fclap (Fortran Command Line Argument Parser) is a modern Fortran library for parsing command-line arguments, inspired by Python’s argparse module. It provides a clean, intuitive API for defining and parsing command-line interfaces in Fortran applications.

Key Features#

  • Familiar API: Designed to mirror Python’s argparse for easy adoption

  • Type Safety: Full support for integer, real, logical, and string argument types

  • Flexible Arguments: Positional arguments, optional flags, and multiple value support

  • Auto-generated Help: Automatic -h/--help output with formatted usage information

  • Subcommands: Support for nested subparsers (like git commit, git push)

  • Argument Groups: Organize arguments logically in help output

  • Mutually Exclusive Groups: Ensure only one of a set of options is used

  • Modern Fortran: Written in Fortran 2008+ with object-oriented design

Quick Example#

program myapp
    use fclap, only: ArgumentParser, Namespace

    type(ArgumentParser) :: parser
    type(Namespace) :: args
    character(len=256) :: filename
    logical :: verbose

    ! Initialize the parser
    call parser%init(prog="myapp", description="Process a file")

    ! Add arguments
    call parser%add_argument("filename", help="Input file to process")
    call parser%add_argument("-v", "--verbose", action="store_true", &
                             help="Enable verbose output")

    ! Parse command line
    args = parser%parse_args()

    ! Use the results
    call args%get_string("filename", filename)
    call args%get_logical("verbose", verbose)

    print *, "Processing:", trim(filename)
    if (verbose) print *, "Verbose mode enabled"
end program myapp

Contents:

Indices and tables#