sub foo {
 local $SWAP = 1;
 alias $alias => $original;
 ...
 Module::bar(some,params);
 ...
}

##</code><code>##

sub bar {
 alias $original => $alias;
 ...
}

##</code><code>##

sub foo {
 {local $SWAP = 1;alias $alias => $original;}
 ...
}