in reply to Re: Avoiding if/else knots II
in thread Avoiding if/else knots II

I'm asking myself what's the advantage of first mapping values to keys and then dispatching the keys via a hash table instead of skipping the key and dispatching directly.

So in all the cases where you have a $key= somethin you could also write down a call of a subroutine handling this key. Except for the default case of course.

I'd write your example like this: 

SWITCH: for ( $myValue ) {
  /$reg2/ && do {
      sub_for_key_a();
      last SWITCH;
    };
  /$reg1/ && do {
      whatever();
      sub_for_key_b();
      last SWITCH;
    };
  #default
    sub_for_default();
} # END SWITCH

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s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

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Re^3: Avoiding if/else knots II
by shmem (Chancellor) on Aug 30, 2006 at 09:43 UTC
    TIMTOWTDI - I wanted to give an example of the m// && do {} idiom which was missing from the OP's previous thread. Since I don't know about the specifics, I wrote it somewhat generic. Depending on cases the $key or $case could be modified etc.

    As for your example, what good is it to use a labelled loop for a list containing one variable? ;-)

    --shmem 

    _($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
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      As for your example, what good is it to use a labelled loop for a list containing one variable? ;-)

      That's easy.

      1. The label is there to show that the block is emulating as a SWITCH statement.
      2. The label is also there to show what the last statements refer to.
      3. the for with just one variable is simply there to assign $value to $_ without explicitly doing it
      4. it's also there to keep the original content of $_ outside the SWITCH ("loop"). Try this 
        my $v="V";
$_="_";
for ( $v ) {
    print "inside: $_\n";
}
print "outside: $_\n";

        [download]
      5. It looks good ;-) (to me). I read this as "switch for value ..."
      s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
      +.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e
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        It looks good ;-) (to me). I read this as "switch for value ..."

        Ah, style. Still, I deem it a misuse of for. It sets up the context of a loop whilst none needed.

        This one looks better (for me, that is :-) 

        # SWITCH
{
  local $_ = $MyValue;
  /$reg2/ && do {
      sub_for_key_a();
      last;
    };
  /$reg1/ && do {
      whatever();
      sub_for_key_b();
      last;
    };
  #default
    sub_for_default();
} # END SWITCH

        [download]
        since a bare block does the job and is less clutter. And I also read it as "switch for $MyValue" ;-)

        --shmem 

        _($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
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