[TUHS] The UNIX Command Language (1976)

[Steffen Nurpmeso]

arnold at skeeve.com wrote in
 <202012011639.0B1GdjcD031722 at freefriends.org>:
 |> On Tue, Dec 1, 2020 at 8:39 AM <arnold at skeeve.com> wrote:
 |>> It was recognized that goto was not necessary if one had proper control
 |>> structures in a language (if/else, while), and that code with no (or
 |>> minimal) gotos was easier to read and understand.
 |
 |Warner Losh <imp at bsdimp.com> wrote:
 |> This is true for simple flow control. However, when you had to break \
 |> out of
 |> multiple levels, or continue not the inner loop, but the middle loop, the
 |> use of extra booleans sure made the code less understandable than \
 |> a 'goto'
 |> a label that stood in for that purpose... This was something that wasn't
 |> well understood by language designers, and even today C and C++ neither
 |> have good flow control beyond the basics. Even though both break and
 |> continue could take an optional count without breaking old code....
 |
 |Quite true. Modern Bourne shells let you supply a number to break and
 |continue to specify how many loops to break.  Ada, or maybe it was one of
 |the Modula-X languages, let you put a label on a loop so that you could
 |say `continue outer' or `break outer' and not need the booleans.

Bah, and perl could and obsoleted it, or at least jumping into
blocks (not crossing initializers)!  You now write code like

      my $ogoditisanewperl = 0;

      if(defined($nl = $self->begin_line)){
         $self->begin_line(undef);
         $self->seen_endl(1);
         $ogoditisanewperl = 1 #goto jumpin;
      }

      while($ogoditisanewperl || ($nl = readline $self->infh)){
         if(!$ogoditisanewperl){
            ++${$self->__lineno};
            $self->seen_endl($nl =~ s/(.*?)\s+$/$1/)
         }
         $ogoditisanewperl = 0; #jumpin:

or even have to work with closures or whatever, or the worst, code
duplication.

 |This is something that newer languages (C#, Java, Go, ...) could have \
 |picked
 |up but didn't, which I think is too bad.

Never without my goto:, and if it is only to break to error
handling and/or staged destruction of local variables after
initialization failures.  Traumatic school impression, finding
yourself locked in some PASCAL if condition, and no way to go to.

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)