I'd actually keep the no-whitespace requirement considering such simple problems like:

    eval q{
        sub foo1 { ... }
    );
    print <<END;
        You'll need to define your method like:
        sub myMethod { ... }
END
use strict;
{
    my $static;
    sub usesStatic {
        # Note that this routine fails if it
        # gets moved out of this lexical scope.
        return $static;
    }
}
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It isn't perfect, but I find the no-whitespace requirement much saner.