s/// w/o intermediate variables?

Here's an example of a recurrent annoyance:

  my $package = 'Foo::Bar::Baz';
  (my $package_filename = $package) =~ s,::,/,g;
  require $package_filename;
  $package->foobar();

One of my many neurotic little peeves is that, unless code readability
absolutely demands it, I hate defining variables that will be used
only once, such as $package_filename above.  I would like to be able
to do something like

  my $package = 'Foo::Bar::Baz';
  require TRANSFORM[ s,::,/,g, "$package.pm" ];
  $package->foobar();

where TRANSFORM[] stands for an expression in which an "s-expression"
(i.e. one using s///) is applied to a string, and the resulting string
is returned as the result.

Of course, I could define a helper sub to do this:

  sub transform {
    my $s_expression = shift;
    local $_ = shift;
    eval $s_expression;
    die $@ if $@;
    $_
  }

But is there a way to achieve this result without defining such a
helper sub?

kynn

P.S. I couldn't come up with a sufficiently general transform sub such
that its first argument is a qr-quoted regexp.  Is there a way to do
this that approaches the level of generality of the eval kluge above?