The general idea is that perl compiles the entire 'unit' (typically a file, or a string eval), then execute it. There are two exceptions:
  1. A BEGIN block. The block is run right after it is compiled. The block is compiled entirely before it's run.
  2. A use statement. This one is run as soon as it's compiled. One might see a use statement as a require and an import call inside a BEGIN block. The side-effect of a use statement is that the used module is compiled and executed.
So, it your case, the order is (ignoring all the other modules):
  1. Compile main up to the 'use Gbl;' line.
  2. Run 'use Gbl;'. This causes:
    1. Compile Gbl.pm.
    2. Run the code in the Gbl package.
    3. Call 'Gbl->import' (if Gbl::import is defined).
  3. Compile the BEGIN block.
  4. Execute the code in the BEGIN block.
  5. Compile the rest of main.pl.
  6. Run main.pl (except the already run use statements and BEGIN blocks).

In reply to Re: BEGIN vs initialization by JavaFan
in thread BEGIN vs initialization by Wiggins

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