Try this for SetLog:

sub SetLog {
  my $glob = shift;
  *LogFile = *$glob;
}
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Update: *LogFile = *{shift()} also works.

In general, though, I would avoid using barewords as file handles in this case and use scalars instead. "Advanced Perl" came out over 10 years ago, and a lot of practices have changed since then. (Update: I suppose you could have the 2005 edition, but still...) To pass file handles around it's just better to use scalar refs:

package test_a;
my $LOGFH;
sub SetLog {
  $LOGFH = shift;
}
sub TestLog {
  print $LOGFH "test_a::TestLog...\n";
}

package main;
...
test_a::SetLog(\*LOGF);
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