OpenEuphoria

Re: Euphoria features

• Posted by Everett Williams <rett at GVTC.COM> Nov 15, 1999
• 776 views

On Mon, 15 Nov 1999 11:17:37 -0800, Cuny, David at DSS <David.Cuny at
DSS.CA.GOV> wrote:

>Everett Williams writes:
>
>> In addition, nobody has addressed my question
>> about the scoping effects of gotos.
>
>I'd assume the following constraints:
>
>1. GOTOs limited to the same routine. I arbitrarily disallow in-line GOTOs.
>
>2. Only forward GOTOs:
>
>    foo:
>    -- NOT ALLOWED
>    goto foo:
>
>3. You can leap out of block structures:
>
>    for i = 1 to 10
>      for j = 1 to 10
>        if x = 12 then
>          goto label:
>        end if
>      end for
>    label:
>    end for

Did I miss something...exit can accomplish this one. If I may borrow
your example.

    for i = 1 to 10
      for j = 1 to 10
        if x = 12 then
          goto label:
        end if
      end for
      ...
      procx()
      ...
    label:
    end for

Exit cannot accomplish this.

So can this.

    for i = 1 to 10
      for j = 1 to 10
        if x = 12 then
          exit
        end if
      end for
      if x != 12 then
         ...
         procx()
         ...
      end if
    end for

It is explicit and costs one more line of code. OR
skip1 = true
    for i = 1 to 10
      for j = 1 to 10
        if x = 12 then
          skip1 = false
          exit
        end if
      end for
      while skip1 do
      ...
      procx()
      ...
      skip1 = false
      end while
    end for

This has the advantage of explicitly describing the range of code to be
skipped and the variable name tells you the purpose of the while(along
with any comments you might have). The goto allows code to be
inadvertently added in the area skipped by the goto with little indication
that it may not be executed at the exit to the for. I also allows selective
skipping. More lines of code that clearly document intent and create
very little extra overhead if I understand what is likely to have to be done
when a goto is encountered.

>4. You can leap into block structures:
>
>    goto label:
>    for i = 1 to 10 do
>    -- NOT ALLOWED
>    label:

Agreed, this is a real non-starter.

>Seems to me that this allows the goal of leaping out of blocks of logic.
>
>-- David Cuny

For your perusal.

Everett L.(Rett) Williams
rett at gvtc.com