With apologies, because I'm sure my question has already been answered but I'm too dense to recognize that fact... :)

If module A "uses" module B, then you want module A's BEGIN block to run before modules B's BEGIN block. When cleanup happens, you want module B's END block to run before module A's END block.

Given these modules

# this is A.pm
package A;

BEGIN { print "Haven't used B yet\n" }
use B;
BEGIN { print "Just used B\n" }


END { print "Exiting A\n" }

1;



# this is B.pm
package B ;

BEGIN {
  # open a file or exit(1) with a message to STDERR
  open B_FH, 'somefile' or exit warn "somefile: $!\n" ;
}

END {
  close B_FH ;
  print "Exiting B\n" ;
}

1;
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If I read your post correctly, you're saying that I want module B's END block to run before module A's END block. If this is what I wanted, I think I'd be disappointed: A use's B, which means that 'use B' in A causes us to fully parse B before finishing parsing A. Therefore, B's END block is loaded before A's END block. This makes A's END block Last In, thereby First Out.

The truth is, I actually don't care in which order ENDs and CHECKs get called. I just want to know why BEGIN/INIT are FIFO and END/CHECK are LIFO.