OpenEuphoria

Re: Discard

• Posted by Hawke <mdeland at NWINFO.NET> Sep 23, 1998
• 503 views

Tom ©upka wrote:
>The "if" substitute hasn't this side-effect; on the
>other hand it is time-consuming - it tests the return
>value every time
>(Can I discard sequences this way?!).
no. 'if..then' can only handle atoms.
to discard a sequence you have to do something like:
-------------------code that prolly won't work :->
include blahblah.e
object junk,Config

procedure discard(object a)
end procedure

function InitGraphics(atom mode)
object VC,success
   if mode=0 then
      success = select_mode(mode)
   else success=graphics_mode(mode)
   end if
   VC=video_config()
   return {success,VC[VC_XPIXELS],VC[VC_YPIXELS]}
end function

--usage #1, i wanna keep the values
Config = InitGraphics(18)

--usage #2, just set the best mode.
if discard(InitGraphics(0)) then end if

--alternate usage#2, just set the best mode
junk =InitGraphics(0)
------------------------------------------
here's the crux of the dilemma: in usage #2a,2b we don't even
want the "return {success,...}" line executed at all, *whatsoever*,
as if it was a remark.

>so I should very appreciate if Euphoria allows function
>call as a statement:
>   my_func()
    --my example:InitGraphics(0)
>The implementation could be simple - the interpreter knows
>that my_func is function so it simply discards the return value.
well, there is more to it than that, as seen above.  this
proposal *won't* get the benefit we wish.  to do that, the return
value must not even be calculated. also, i think it begins to impair
readability and clarity. however!, if the interpreter was to see
this my_func() or InitGraphics(0) on a line by itself, and then
remarked out the "return" line before tokenizing the guts of the
function and executing the guts of the function...
then, we would have something.

still not sure it would be the 'best' way as far as clarity,
and it's looking awful "C'ish" this way...
i'd almost *prefer* the verbosity... hrmmmm....
neigh, i *would prefer* the verbosity of:
  discard=InitGraphics(0)
IF!!! the interpreter did as suggested above (remarking the return)
because it let's others *KNOW* you're throwing it away.

if 'discard' is too verbose, then let's use 'junk'...
2 less wittle letters to type, for those worried about
such things...
[heh, i clock in at 60-90 WPM, so (it != bothers_me)]

take care all
--Hawke'