Loop Control - First?

set_uk has asked for the wisdom of the Perl Monks concerning the following question:

The following section calls a method and dependent on the return either uses last, performs the next command - or what I am after restarts the loop from the beginning. I need a "first" command. Is the best way to do this put another label control around COMMAND - break out of COMMAND to NEWCOMMAND and then reexecute COMMAND?

COMMAND: foreach my $CommandHsh (@{$command_section}){
  
      $Result = $self->ExecuteCommand($CommandHsh);
      if ($Result eq "END"){
        $self->{_logfile}->debug("Signal received to END command secti
+on");
        last COMMAND;
      } elsif ($Result eq "CONTINUE"){
        $self->{_logfile}->debug("Signal received to CONTINUE command 
+section");
        #next COMMAND;
      } elsif ($Result eq "RESTART"){
        $self->{_logfile}->debug("Signal received to RESTART command s
+ection");
        redo COMMAND;
      } else {
        $self->{_logfile}->error("Incorrect exit type from ExecuteComm
+and");
      }
    }

  $self->{_logfile}->info("End of CommandSection");

}
[download]

This appears to work but is it the best way:-


RESTART: while ( 1 ) {
  COMMAND: foreach my $CommandHsh (@{$command_section}){
    
        $Result = $self->ExecuteCommand($CommandHsh);
        if ($Result eq "END"){
          $self->{_logfile}->debug("Signal received to END command sec
+tion");
          last COMMAND;
        } elsif ($Result eq "CONTINUE"){
          $self->{_logfile}->debug("Signal received to CONTINUE comman
+d section");
          #next COMMAND;
        } elsif ($Result eq "RESTART"){
          $self->{_logfile}->debug("Signal received to RESTART command
+ section");
          next RESTART;
        } else {
          $self->{_logfile}->error("Incorrect exit type from ExecuteCo
+mmand");
        }
      }

  $self->{_logfile}->info("End of CommandSection");
  last RESTART;
}
[download]

Comment on Loop Control - First? Select or Download Code

Replies are listed 'Best First'.
Re: Loop Control - First? by hmerrill (Friar) on Oct 28, 2003 at 14:35 UTC
Just my preference, but I prefer to do things like that slightly differently - I don't like to "mix" the loops: RESTART: while ( 1 ) { COMMAND: foreach my $CommandHsh (@{$command_section}){ $Result = $self->ExecuteCommand($CommandHsh); $Restart = 0; # set to false if ($Result eq "END"){ $self->{_logfile}->debug("Signal received to END command secti +on"); last COMMAND; } elsif ($Result eq "CONTINUE"){ $self->{_logfile}->debug("Signal received to CONTINUE command +section"); #next COMMAND; } elsif ($Result eq "RESTART"){ $self->{_logfile}->debug("Signal received to RESTART command s +ection"); $Restart = 1; # set to true } else { $self->{_logfile}->error("Incorrect exit type from ExecuteComm +and"); } } ### end COMMAND foreach next RESTART if $Restart; ### only get here if NOT restarting - finish up ### $self->{_logfile}->info("End of CommandSection"); last RESTART; } [download] HTH.	[reply] [d/l]
Re: Loop Control - First? by simonm (Vicar) on Oct 28, 2003 at 15:35 UTC
The outer block doesn't need to be a loop; a plain block is sufficient: ATTEMPT: { COMMAND: foreach my $CommandHsh (@{$command_section}){ $Result = $self->ExecuteCommand($CommandHsh); if ($Result eq "END"){ $self->{_logfile}->debug("Signal received to END command secti +on"); last COMMAND; } elsif ($Result eq "CONTINUE"){ $self->{_logfile}->debug("Signal received to CONTINUE command +section"); next COMMAND; } elsif ($Result eq "RESTART"){ $self->{_logfile}->debug("Signal received to RESTART command s +ection"); redo ATTEMPT; } else { $self->{_logfile}->error("Incorrect exit type from ExecuteComm +and"); } } $self->{_logfile}->info("End of CommandSection"); } [download]	[reply] [d/l]
Re: Loop Control - First? by Abigail-II (Bishop) on Oct 28, 2003 at 16:39 UTC
The outer block doesn't even need to exist. If you use a goto, the solution will be more symmetric (yeah, getting more pleasing looking code by using goto!): COMMAND: foreach my $CommandHsh (@{$command_section}){ $Result = $self->ExecuteCommand($CommandHsh); if ($Result eq "END"){ $self->{_logfile}->debug("Signal received to END command secti +on"); last COMMAND; } elsif ($Result eq "CONTINUE"){ $self->{_logfile}->debug("Signal received to CONTINUE command +section"); next COMMAND; } elsif ($Result eq "RESTART"){ $self->{_logfile}->debug("Signal received to RESTART command s +ection"); goto COMMAND; } else { $self->{_logfile}->error("Incorrect exit type from ExecuteComm +and"); } } $self->{_logfile}->info("End of CommandSection"); [download] Abigail	[reply] [d/l]
Re: Loop Control - First? by dragonchild (Archbishop) on Oct 28, 2003 at 15:01 UTC
Personally, I'd use some form of signals. Not the $SIG{INT} stuff. More like try-catch signals. ------ We are the carpenters and bricklayers of the Information Age. The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6 ... strings and arrays will suffice. As they are easily available as native data types in any sane language, ... - blokhead, speaking on evolutionary algorithms Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.	[reply]