OpenEuphoria

Re: [DOS] Can we emulate "pass by reference" in Eu?

• Posted by Alex Caracatsanis <CaracatsanisA at ramsayhealth.com.au> Oct 19, 2004
• 496 views

Alex Caracatsanis wrote:
> 
> Dear List
> 
> For my general knowledge, rather than with a specific program in mind, I'd
> like to
> ask how to pass a non-global variable (two scenario's: an atom; a sequence) as
> an argument
> to:
> 1 a procedure that changes the variable (eg increments it)
> 2 a function that changes the variable (eg increments it) but returns some
> other, different,
> variable
> 
> A "minimal" example to achieve the above, would be enough.
> 
> Thank you
> 
> Alex Caracatsanis
> 

Maybe I should add: what I'm thinking about is something like this...

procedure incrementProcedure( object obj )
  -- code that will increment the actual parameter (num),
  -- not a copy of it, such that num is now 11 or {11, 21}
end procedure

function incrementFunction( object obj )
  object retVar

  -- code that will increment the actual parameter (num),
  -- not a copy of it, such that num is now 12 or {12, 22}
  -- code to do other things as well

  return retVar
end function  

procedure main()
  atom num  num = 10
  sequence seq  seq = {10, 20}
  object retVal

  incrementProcedure( num )
  ? num  -- now num = 11
  
  retVal = incrementFunction( num )
  ? num  -- now num = 12
  -- retVal is anything; not interested in it for now

  incrementProcedure( seq )
  ? seq  -- now seq = {11, 21}

  retVal = incrementFunction( seq )
  ? seq  -- now seq = {12, 22}
  -- retVal is anything; not interested in it for now
end procedure

main()

Hope that's clear.

Thanks

Alex Caracatsanis