How can I echo the result of function with a range?

Question

If I have a function that takes a range, how can I echo the return value of the function?

For example, the following does not work:

:echo 2,8call MyFunction()

Answer 1

I looked into this, and I could not find a direct way of doing it. However, one possibility is to create an auxiliary function, that is:

function! Range() range abort
  return RangeAux(a:firstline, a:lastline)
endfunction

function! RangeAux(lnum1, lnum2) abort
  echo a:lnum1
  echo a:lnum2
endfunction

1,3call Range()
call RangeAux(1,3)

Answer 2

@Karl's answer is pretty good but you can also use execute():

echo execute("1,2call Range()")

You can even use variables for the range:

let l1=1
let l2=2
echo execute(l1 . "," . l2 . "call Range()")

Answer 3

Using call you are not able to get the return value of the function, regardless whether range is used or not.

Aside from @Karl's answer, you can set some variable instead of using return. Such as

function! Range() range abort
  let toreturn = 'my value'
  let s:retval = toreturn
endfunction