I needed a super-simple way to have a log file for a script that uses some modules of mine, and I wanted the modules to write to the same log file as the script. Here's what I came up with.

In my script:

#!/opt/perl/bin/perl

use strict;
use warnings;

use lib '.';
use MyModule;

# ----------
open(my $logfile, '>>', 'blah.log')
  or die "Couldn't open log file.";

sub my_logging_fn {
    my ($log_msg) = @_;
    print {$logfile} $log_msg, "\n";
}

# ----------
# Set up MyModule to use our logging function.
MyModule::set_logger_fn(\&my_logging_fn);

# ----------
# main
my_logging_fn("Doing something in the script.");
MyModule::do_some_work();
my_logging_fn("Ok, that's all for now.");

[download]

And in MyModule.pm:

package MyModule;

# Before calling any functions in this module,
# be sure to first call `set_logger_fn(...)`.

my $log_fn_ref;

sub set_logger_fn {
    my ($fn_ref) = @_;
    $log_fn_ref = $fn_ref;
}

# ----------
sub do_some_work {
    # ...
    # write a log message.
    $log_fn_ref->("Doing some work in MyModule::do_some_work()");
    # ...
}

1;

[download]

If you see any ways this is broken, please let me know!

In reply to my homemade solution to logging (module writes to same log file as the script). What do you think? by Anonymous Monk

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