I am learning Modern Perl. The perl file chapter5_2.pl have code : 
#!/bin/perl
use v5.14.2;
use strict;
use Carp;


package main;

main();

sub main
{
    show_call_information();
}

sub show_call_information
{
    my ($package, $file, $line,$func) = caller(0);
    say "Called $func from $package in $file:$line";
}

say "---------use Carp------------------";

say add_numbers(1,2,3);

sub add_numbers
{
    croak 'Expected two numbers, received:' . @_
    unless @_ == 2;
    my ($one, $two) = @_;
    return $one + $two;
}

[download]
I run as 
   perl chapter5_2.pl

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get the following output: 
 Called main::show_call_information from main in chapter5_2.pl:13
---------use Carp------------------
Expected two numbers, received:3 at chapter5_2.pl line 28.
    main::add_numbers(1, 2, 3) called at chapter5_2.pl line 24

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I can't know why the main() function is called automatically? What's the mechanism?

How can I get result from formal document such as perldoc?

Thanks!

In reply to why main() call automatically? by Thai Heng

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