Re: simpliest way to add "language" to my app

Something that's relatively simple is to have a hash, with the keys being the command, and the values being anonymous subroutines.

 my %command=
  (
     shutdown    => sub { print "Shutting down...\n"; exit 0; },
     lock_user   => sub { my ($user) = @_;
                      # Insert code to lock $user here.
                    },
     unlock_user => sub { my ($user) = @_;
                      # Insert code here to unlock $user
                    },
     show        => sub {  # Insert show code here
                    },
     lock        => sub {
                        $_ = shift;
                        if ($command{lock_$_}) {
                           $command{lock_$_}->(@_);
                        } else {
                           die "Don't know how to lock $_\n";
                        }
                    },
     unlock      => sub {
                        $_ = shift;
                        if ($command{unlock_$_}) {
                           $command{unlock_$_}->(@_);
                        } else {
                           die "Don't know how to unlock $_\n";
                        }
                    },
      help        => sub {# update per L~R's suggestion:
                         print "Current commands: ";
                         print join "\n", sort {
                         $a cmp $b } keys %command;
                    },
   );

  my ($cmd, @args) = @ARGV; # Or however you get them.
  $cmd = lc $cmd; # Force lowercase per L~R's suggestion.
  my $sub = $command{$cmd};
  $sub = $command{help} if not defined $sub;
  $sub->(@args);
[download]

$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/
[download]

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Re: Re: simpliest way to add "language" to my app by Limbic~Region (Chancellor) on Oct 05, 2003 at 04:03 UTC
jonadab, Depending on how forgiving and user friendly smackdab wants to be, your solution can be improved: Pass raw data to parsing sub If match found, execute accordingly If match not found, give user a list of currently supported commands The parsing sub may do things like: Force lower case Change (un)?lock user (un)?lock_user Allow synonyms such as halt for shutdown Regular expressions to handle common typos Append non matches to a log for further analysis to help improve parsing routine The only other thing that I would suggest is changing the key assignment from anonymous subs to named subs. `shutdown => sub { print "Shutting down...\n"; exit 0; } becomes shutdown => \&shutdown` [download] Cheers - L~R	[reply] [d/l]
Re: simpliest way to add "language" to my app by jonadab (Parson) on Oct 05, 2003 at 04:20 UTC
Pass raw data to parsing sub Well, he said the simplest way... If match not found, give user a list of currently supported commands Now, that would certainly be a worthwhile enhancement. And easy enough to do, too. Force lower case I almost included that... but for some reason I didn't. Perhaps I should have. Allow synonyms such as halt for shutdown That may be the best argument for the named subs you mention, actually. `$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}} split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/` [download]	[reply] [d/l]
Re: Re: simpliest way to add "language" to my app by smackdab (Pilgrim) on Oct 05, 2003 at 04:38 UTC
Thanks these are helpful to look at. I am currently using one big switch in a ParseCmd() fn, which is easier for me as each "response" is short. What is a mess is validating that each command has the correct number of parameters before I call it. Come to think about it I guess each command fn could exit with an "invalid command" error if there are missing params...I see that your approach handles this much better that what I am doing...just pass an array for the "rest" of the params (if any) Still a little wordy if I add 50 commands in the future...but simple! thanks	[reply]