File Coverage

blib/lib/Acme/Drunk.pm

Criterion	Covered	Total	%
statement	29	34	85.2
branch	2	4	50.0
condition	3	6	50.0
subroutine	10	13	76.9
pod	4	10	40.0
total	48	67	71.6

package Acme::Drunk;
use strict;

require Exporter;
use base qw[Exporter];
use vars qw[$VERSION @EXPORT %EXPORT_TAGS];

$VERSION     = '0.03';
@EXPORT      = qw[MALE FEMALE drunk floz_to_etoh proof_to_percent];
%EXPORT_TAGS = ( ':all' => \@EXPORT );

sub ML_IN_FLOZ () { 0.0338140226 }

sub   MALE () { 0 }
sub FEMALE () { 1 }

# Widmark r factor (reduced body mass).
# Men:   0.50-0.90 avg 0.68.
# Women: 0.45-0.63 avg 0.55.
sub   MALE_WIDMARK_R () { 0.68 }
sub FEMALE_WIDMARK_R () { 0.55 }

# Widmark beta factor (alcohol metabolized per hour).
# Between 1.0% and 2.4%, avg 1.7%.
sub WIDMARK_BETA () { 0.017 };

# Ethyl Alcohol weight in pounds.
sub ETOH_WEIGHT () { 0.0514 }

# 1987, Fitzgerald & Hume discover specific
# gravity of blood is important, at 1.055 g/ml.
sub GRAVITY_OF_BLOOD () { 1.055 }

# Body Alcohol Concentration
sub bac {
    my ($body_weight, $alcohol_weight) = @_;
    $alcohol_weight / $body_weight * 100;
}

# Portion of body that holds alcohol.
sub bha {
    my ($body_weight, $gender) = @_;
    $body_weight * ( $gender == MALE ? MALE_WIDMARK_R : FEMALE_WIDMARK_R );
}

# Water Tissue Alcohol Concentration
sub wtac {
    my ($body_weight, $alcohol_weight, $gender) = @_;
    bac( bha($body_weight, $gender), $alcohol_weight );
}

# Proof goes to 200.
sub proof_to_percent {
    my ($proof) = @_;
    $proof / 2;
}

# For N fluid ounces of alcohol, find pure alcohol content.
sub floz_to_etoh {
    my ($ounces, $percent) = @_;
    $ounces * $percent;
}

# For N ml of alcohol, find pure alcohol content.
sub ml_to_etoh {
    floz_to_etoh( $_[0] * ML_IN_FLOZ, $_[1] );
}

# Convert fluid_ounces of EtOH to weight in pounds.
sub etoh_to_lbs {
    my ($ounces) = @_;
    $ounces * ETOH_WEIGHT;
}

# multiply wtac with gravity of blood.
sub consider_gravity {
    my ($alcohol_weight) = @_;
    $alcohol_weight * GRAVITY_OF_BLOOD;
}

# Remove metabolized alcohol over drinking time.
sub remove_metabolized_alcohol {
    my ($alcohol_weight, $hours) = @_;
    $alcohol_weight - ( $hours * WIDMARK_BETA );
}

# Are you drunk?
sub drunk {
    my (%params) = @_;
    $params{gender} = MALE unless defined $params{gender};
    $params{body_weight}    ||= 150;
    $params{hours}          ||= 2;
    $params{alcohol_weight} = consider_gravity( etoh_to_lbs( $params{alcohol_weight} || 3 ) );

    my $concentration = wtac( @params{qw[body_weight alcohol_weight gender]} );
       $concentration = remove_metabolized_alcohol( $concentration, $params{hours} );

    return $concentration;
}

1;

__END__