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**************************************************************************
* The following are notes for all the Perl tracing scripts,
*
* $Id: ALLperl_notes.txt 44 2007-09-17 07:47:20Z brendan $
*
* COPYRIGHT: Copyright (c) 2007 Brendan Gregg.
**************************************************************************
* Where did those "BEGIN" subroutine calls come from?
The following counts subroutines from the example program, Code/Perl/hello.pl,
# pl_subcalls.d
Tracing... Hit Ctrl-C to end.
^C
FILE SUB CALLS
no subroutines were called, so there is no data to output.
Now a similar program is traced, Code/Perl/hello_strict.pl, which uses
the "strict" pragma,
# pl_subcalls.d
Tracing... Hit Ctrl-C to end.
^C
FILE SUB CALLS
hello_strict.pl BEGIN 1
strict.pm bits 1
strict.pm import 1
not only were functions from "strict.pm" traced, but a "BEGIN" function
ran from the "hello_strict.pl" program - which doesn't appear to use "BEGIN",
# cat -n ../Code/Perl/hello_strict.pl
1 #!./perl -w
2
3 use strict;
4
5 print "Hello World!\n";
Perl appears to add a BEGIN block to process the "use" keyword. This makes
some degree of sense.
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