OpenEuphoria

Re: case and foreach

• Posted by Derek Parnell <ddparnell at bigpond.com> Apr 01, 2005
• 550 views

codepilot Gmail Account wrote:
> 
> Pros
> I think foreach could be used to add some parallelism to euphoria and
> simplify a few things that for loops and subscripting are used for.

I can relate some experience here. The D language recently introduced
a 'foreach' construct, and I have been using it where ever I can. It has
made a huge difference by making code more easy to create, read and maintain.

The syntax it uses is (in Euphoria-like code) ...

   for each [idx,] elem in seq do
    . . .
   end for

where the 'elem' is an object whose scope is restricted to the 'for' loop
and the optional 'idx' is an integer that contains the index number for
'elem' - its scope is also the 'for' loop. The code inside the loop uses
'elem' as if it was 'seq[idx]'. You can read 'elem' *and* write to 'elem'.

For example:

   for each Line_Cnt, Line in TextFile do
      if Line_Cnt = 1 then
         doPrintHeading()
      end if
      
      if length(Line) != 0 then
          if Line[1] = '*' then
              Line = "(comment) " & Line[2..$]
          end if
      end if
      PrintLine(LineCnt, Line)

      if Line_Cnt = length(TextFile) then
         doPrintTrailer()
      end if
   end for

Altering the length of the source sequence is permitted, but you are just
asking for trouble if you start that sort of thing.

> Case would be good for simplifying if/elsif/else blocks to a more
> manageable level and could also help in optimization.

Of course a 'case' construct would made code more readable and easier to
maintain, but when has *that* ever been a priority. If fact, 'while' and
'for' are for wimps and coding gromets 

> Cons
> Does anyone have something against case or foreach(element in a
> sequence) in euphoria?

Well, it does mean more work for anyone trying to implement the Euphoria
language. So maybe we should all just forget about beating this dead horse;
it ain't ever going to get up.


(Did that come over as a little on the bitter side? Sorry if it did.)

-- 
Derek Parnell
Melbourne, Australia
irc://irc.sorcery.net:9000/euphoria