• bearophile (44/44) Jun 09 2013 This comes from a small thread in D.announce.
• Jonathan M Davis (6/7) Jun 09 2013 Why not just use labeled breaks on switches too? Then it would be more i...
• Timon Gehr (19/23) Jun 09 2013 Are you aware that the following works?
• Jonathan M Davis (3/31) Jun 09 2013 Well then, there you go. Problem solved.
• bearophile (6/24) Jun 09 2013 Of course I wasn't aware of that :-) I have never seen that in

"bearophile" <bearophileHUGS lycos.com> writes:

This comes from a small thread in D.announce.

Sometimes you have loops inside switch cases, maybe like this, 
and you want to exit the current switch case instead of just the 
loop (or the loops):


void main() {
     import std.stdio;
     enum Foo { foo1, foo2 }
     int[5] data;
     Foo f;

     switch (f) {
         case Foo.foo1:
             foreach (x; data)
                 if (x == 10)
                     goto END;
             writeln("10 not found.");
             data[0] = 10; // Put the missing 10.
             END:
             break;

         default:
             break;
     }
}


In some of such situations sometimes I'd like a nicer way to exit 
the case, maybe with a "break switch":


     switch (f) {
         case Foo.foo1:
             foreach (x; data)
                 if (x == 10)
                     break switch;
             writeln("10 not found.");
             data[0] = 10; // Put the missing 10.
             break;



A "break switch" is a bit like the D "break label", that allows 
to break an outer loop:

loop1:
foreach (x; items1)
   foreach (y; items2)
     if (foo(x, y))
       break loop1;


"break switch" in general is useful to express more clearly the 
programmer intentions when there are loops inside switch cases.

Do you like? :-)

Bye,
bearophile

Jonathan M Davis <jmdavisProg gmx.com> writes:

On Monday, June 10, 2013 01:23:23 bearophile wrote:
 Do you like? :-)

Why not just use labeled breaks on switches too? Then it would be more in line 
with how it works with loops, _and_ it would give the capability of exiting 
multiple switch statements at once, which your break switch suggestion does 
not.

- Jonathan M Davis

Timon Gehr <timon.gehr gmx.ch> writes:

On 06/10/2013 01:23 AM, bearophile wrote:
 ...

 Do you like? :-)

 Bye,
 bearophile


Are you aware that the following works?

void main(){
     import std.stdio;
     enum Foo{foo1,foo2}
     int[5] data;
     Foo f;
     Lswitch:switch(f){
     case Foo.foo1:
         foreach (x;data)
             if(x==10)
                 break Lswitch;
         writeln("10 not found.");
         data[0] = 10; // Put the missing 10.
         break;

     default:
         break;
     }
}

Jonathan M Davis <jmdavisProg gmx.com> writes:

On Monday, June 10, 2013 01:36:25 Timon Gehr wrote:
 On 06/10/2013 01:23 AM, bearophile wrote:
 ...
 
 Do you like? :-)
 
 Bye,
 bearophile

 
 Are you aware that the following works?
 
 void main(){
      import std.stdio;
      enum Foo{foo1,foo2}
      int[5] data;
      Foo f;
      Lswitch:switch(f){
      case Foo.foo1:
          foreach (x;data)
              if(x==10)
                  break Lswitch;
          writeln("10 not found.");
          data[0] = 10; // Put the missing 10.
          break;
 
      default:
          break;
      }
 }

Well then, there you go. Problem solved.

- Jonathan M Davis

"bearophile" <bearophileHUGS lycos.com> writes:

Timon Gehr:

 Are you aware that the following works?

 void main(){
     import std.stdio;
     enum Foo{foo1,foo2}
     int[5] data;
     Foo f;
     Lswitch:switch(f){
     case Foo.foo1:
         foreach (x;data)
             if(x==10)
                 break Lswitch;
         writeln("10 not found.");
         data[0] = 10; // Put the missing 10.
         break;

     default:
         break;
     }
 }

Of course I wasn't aware of that :-) I have never seen that in 
docs, or D code. It's an acceptable solution, better than the 
goto.

Thank you,
bearophile