local *FH;  # need this if in a loop or repeated sub
open FH, 'blah' or die "can't open blah: $!\n";

$$LOG{$foo}[$blah] = \*FH;

$in = readline($$LOG{$foo}[$blah]);  # don't try <>, it doesn't like complex structures
print {$$LOG{$foo}[$blah]} $out;  # must use a block {} for the filehandle