OpenEuphoria

Re: The fate of Euphoria

• Posted by Patrick Barnes <mrtrick at gmail.com> Nov 08, 2004
• 570 views

> Patrick:
>    Where did you find "  next(N)  " instruction ?
> 
> Bernie

I said... *IF* they are available. Unfortunately Rob hasn't
implemented all of the high-level program flow constructs.

for a = 1 to 10 do
          *lots of code*
           if something then [I want to skip the rest of the block,
but stay within the loop] end if
           *lots more code*
end for

At the moment, we have to encase the 'lots more code' within an if
statement. Unfortunately, this often leads to horrible amounts of
indenting. In C and Java, the 'continue' statement causes the program
to start executing again at the beginning of the loop, incrementing
the loop variable.
In Euphoria, hopefully ''next' or 'continue' could do the same thing...


The other thing missing is control over the exit/next statement's
scope. If you have this:

for x = 1 to SCREEN_WIDTH do
for y = 1 to SCREEN_HEIGHT do
         *code*
         *code*
          [I've found what I'm looking for, I want to exit out of
these 'for' loops]
         *code*
end for
end for

Using just plain 'exit' won't work. You need to do this:

integer exit_flag exit_flag = 0
for x = 1 to SCREEN_WIDTH do
for y = 1 to SCREEN_HEIGHT do
         *code*
         *code*
          --[I've found what I'm looking for, I want to exit out of
these 'for' loops]
         if something_is_true then
                 exit_flag = 1
                 exit
         end if
         *code*
end for
      if exit_flag then exit end if
end for

Not only is it harder to understand, it is slower, because the program
has to keep checking exit_flag every time it iterates through...
Adding something like exit(N), where N is the number of loops to exit
out of, would make life much easier. If there are concerns about
readability, loops could be given an OPTIONAL label:
for x = 1 to 10 as outer_x do 
OR 
while 1 as main_loop do. 
That way, exit( label ) would move out of the loop with that label,
and continue executing code right after the end for / end while of
that loop. (label is not of any type, and cannot be read, written, or
referred to in any other way.)


-- 
MrTrick