This is more a joke than a real solution, still might be useful. This builds a Perl routine via eval and then calls it from the content of your own page. It works more or less like a JSP compiler, turning the page data into native source code, and then compiling it via eval. If you add a thin layer of error control, this might be a viable solution.

The routine it creates expects a hash containing true/false values (the same you will test in your page) and returns a string with the results.

my $code = "";
my %H;

while (<DATA>) {
    chomp;
    
    if ( /<%\s*if (.+?)\s*%>/i ) {
        $code .= " if (\$H{$1}) { \n";
    } elsif ( /<%\s*elsif (.+?)\s*%>/i ) {
        $code .= "} elsif (\$H{$1}) { \n";
    } elsif ( /<%\s*else\s*%>/i ) {
        $code .= "} else { \n ";
    } elsif ( /<%\s*endif\s*%>/i ) {
        $code .= "};\n ";
    } else {
        $code .= "  \$r .= \"$_\";\n";
    }
    
}


$code = "sub page_expr\n {\n my (%H) = \@_; my \$r = '';\n $code\n; re
+turn \$r }; ";
eval $code;
    
$H{boys} = 1;
$H{nice_boys} = 1;

print page_expr( %H );
     

__DATA__
<%IF boys %>
  &nbspYou can play football for the whole day.
   <%IF nice_boys %>
    &nbspYou don't need to get permission from your teacher.
   <%ELSIF agreesive_boys%>
    &nbspPlease respect others
   <%ELSE%>
    &nbspPlease talk to me first
   <%ENDIF%>
<%ELSIF girls%>
  &nbspI suggest you to go to library
<%ELSE%>
  &nbspStay here
<%ENDIF%>
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This creates dynamically this code (I reformatted it a bit just to make it more readable):

sub page_expr {
 my (%H) = @_; my $r = '';
  if ($H{boys}) {
    $r .= "   You can play football for the whole day.";
    if ($H{nice_boys}) {
      $r .= "     You don't need to get .";
    } elsif ($H{agreesive_boys}) {
      $r .= "     Please respect others";
    } else {
      $r .= "     Please talk to me first";
    };
  } elsif ($H{girls}) {
   $r .= "   I suggest you to go to library";
  } else {
   $r .= "   Stay here";
  };
  return $r;
};

When run, this program prints:

   You can play football for the whole day.    
   You don't need to get permission from your teacher.

Just my euro 0.02. Hope it helps.




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