This looks like a perfect place for the under-appreciated nonlocal loop control operators, e.g.:

@sources = (
    { pre => [sub { print 1; }, sub { print 2; last pre; }, sub { prin
+t 3 }],
      post => [sub { print 4; }, sub { print 5; last source }] },
    { pre => [sub { print "badness" }] }
);

source: for (@sources) {
 pre: for (@{$_->{pre}}) {
        $_->();
    }
 post: for (@{$_->{post}}) {
        $_->();
    }
}
__END__
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Document a good set of labels, and your module will be both convenient to use and educational about Perl's dark corners.

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