Enumerations

prik turns supported Fortran enum declarations into typed integer constants. It does not generate Python Enum or IntEnum classes — values remain plain integers with the resolved dtype.

Complete Example

Create colors.f90:

module colors_api
  implicit none

  enum, bind(C)
    enumerator :: red = -1
    enumerator :: blue
    enumerator :: green = 10
    enumerator :: yellow
  end enum

contains

  integer(4) function round_trip_color(value) result(output)
    integer(4), intent(in) :: value
    output = value
  end function round_trip_color

end module colors_api

Build it:

python3 -m prik colors.f90 --out-dir build/colors

Usage in Python

import sys

sys.path.insert(0, "build/colors")
from colors.colors_api import blue, green, red, round_trip_color, yellow

print(red, blue, green, yellow)  # -1 0 10 11

# Pass enumerator values to procedures
result = round_trip_color(green)
print(result)                    # 10

Key Points

  • Enumerators become module constants declared with Final[...] in the generated semantic .pyi; the native enumerator value cannot change.
  • They use the resolved integer dtype (usually Int32).
  • Rebinding an imported name in Python only creates a local shadow — it does not change the native value.
  • No automatic runtime validation — passing any integer of the correct dtype works.
  • Static type checkers see them as integer constants.

Limitations

  • No native Enum class is generated in Python.
  • If you want a proper Python Enum, define one in your application code and pass .value (as np.int32).

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