MooseX-Role-DryRunnable

For many reasons can be interesting change the behavior of some methods using some configuration. For example, there is a special mode, called "dry run", where we can avoid some instructions (like delete/insert/update data) in order to run the system in the product environment and produce log of any operations.

There are many ways: extend the class to override some methods and trigger the option dry_run using some proxy, add if/else manually in each method, using (AOP) Aspects Oriented Programming (Aspect or Moose around). I choose, to solve this problem, the Moose around with AOP approach.

This module is a Moose Role who require two methods, is_dry_run and on_dry_run, the first method return true if we are in this mode (reading from a configuration file, command line option or some environment variable) and the second receive the name of the method and the list of arguments. Consider the example below:

package Foo;
use Data::Dumper;
use Moose;

with 'MooseX::Role::DryRunnable' => { 
  methods => [ qw(bar) ]
};

has dry_run => (is => 'ro', isa => 'Bool', default => 0);

sub bar {
  shift;
  print "Foo::bar @_\n";
}

sub is_dry_run { # required !
  shift->dry_run
}

sub on_dry_run { # required !
  my $self   = shift;
  my $method = shift;
  $self->logger("Dry Run method=$method, args: \n", @_);
}

In this case, if we set the attribute dry_run to true, instead call the content of Foo::bar method, we call on_dry_run passing the method name and arguments to log (or do something different, you choose).

Attributes - EXPERIMETAL

To put the information about the dry run capability close to the method, there is an Attribute called :dry_it.

package Foo;
use Data::Dumper;
use Moose;
use MooseX::Role::DryRunnable::Attribute;
with 'MooseX::Role::DryRunnable::Base';

has dry_run => (is => 'ro', isa => 'Bool', default => 0);

sub bar :dry_it {
  shift;
  print "Foo::bar @_\n";
}

sub is_dry_run { # required !
  shift->dry_run
}

sub on_dry_run { # required !
  my $self   = shift;
  my $method = shift;
  $self->logger("Dry Run method=$method, args: \n", @_);
}

Unfortunately, this attribute is injected in the UNIVERSAL. It is Experimental. Be Careful.

Test Coverage

100% code coverage by 3 tests.

--------------------------- ------ ------ ------ ------ ------ ------ ------
File                           stmt   bran   cond    sub    pod   time  total
---------------------------- ------ ------ ------ ------ ------ ------ ------
...ooseX/Role/DryRunnable.pm  100.0    n/a    n/a  100.0    n/a   70.5  100.0
.../DryRunnable/Attribute.pm  100.0  100.0    n/a  100.0    n/a   24.3  100.0
.../Role/DryRunnable/Base.pm  100.0    n/a    n/a  100.0    n/a    5.2  100.0
Total                         100.0  100.0    n/a  100.0    n/a  100.0  100.0
---------------------------- ------ ------ ------ ------ ------ ------ ------