maxwilliams94/result-fortran

An attempt at emulating some of the functionality available in Rust for return, propagation and handling of errors

Plan

Type Layout

Result

type Result
    type(T) :: Ok
    type(Error) :: Err = Error("", "", 0)
    logical :: E = .false.
end type Result

Error

type Error
    character(*) :: message
    character(*) :: src
    integer :: error_code    
end type Error

Notes

• Should the error type be generic or tailored according to the type of the corresponding value?
  • For now
• Base (abstract?) types for the Result type should minimise repeated code
• Support for allocatable/static arrays

Methods

• Check the E field and return Ok if error free
• Result reading subroutine parses both Ok and Err fields and populates intent(out) arguments with the contents
• If no error, code continues as usual using the Ok value
• On Err
  • Detect that an error has been flagged
  • STOP execution and print error message
  • Return Result instance to calling subroutine for higher level error handling

Initialisation

• Initialise standard error/error output channel units