Re: Secret Perl Operators: the boolean list squash operator, x!!

[radiantmatrix]

Your x!! approach is nifty, but it's a little hard to read: the double-negation is confusing unless explained, and the x operator seems to be out of place in this context. I have always found one of these easier to read:

my $uri;
foreach ( 
   'http://example.net/app',
   $is_admin_link && 'admin',
   $subsite, 
   $mode, 
   $id, 
   $submode,
) {
   $uri.="$_/" if ( defined $_ && length($_) ) #omit undef and empties
}

If you need to preserve the parts seperately:

my @part = ( 
   'http://example.net/app', 
   $is_admin_link   && 'admin',
   $subsite,
   $mode,
   $id,
   $submode,
);

my $uri; 
foreach (@parts) { 
   $uri.="$_/" if ( defined $_ && length($_) ) #omit undef and empties
}

I prefer these because:

1. The logic for inclusion of parts is clear
2. It makes it easy to apply a common rule to all components (e.g. URL-ify components before concatenation)
3. It avoids repetition of code

[Aristotle]

This is basically ioannis’ response, with most repetition removed. All of the points I made in the last paragraph of my response to him apply equally to your suggestion.

[radiantmatrix]

Actually, most of your objections don't seem to apply.

1. I already include the slashes through use of $uri.="$_/"
2. The $is_admin_link && 'admin' is in the right order already

As for the 0/1 problem with $is_admin_link, that's a fault of my assumption that $is_admin_link would either be true or undefined. I agree, that's a bad assumption, but it's a simple fix. I would probably use a single ternary:

$is_admin_link ? 'admin' : undef

[Aristotle]

Read closer. I said “the last paragraph.” Here is said paragraph, in order to avoid further confusion.

Not to mention that all of this misses my point because it’s specific to join, and I’ve needed to pass a variable list to some function or method often enough where really needed the sub-list to be empty depending on the condition – winging it by combining && and the false evaluates to the empty string factoid wouldn’t have done me any good.

Try to simplify a different example to get closer to my point.