perlquestion
stewart_lee
<p> I have module Money/Finance.pm, within it, a sub getMovingAve is defined with protocol of ($$\@\@). I include this module in moveaverage2.pl, if I include it by 'use Money::Finance', I need call it as ($$@@), if I include it by 'require Money::Finance' I need call it as ($$\@\@), exactly matching with how its protocol is defined. Is it a bug or how to explain this difference. By the way, I run this test on HP box with Perl v5.8.8 and I have attached all both souce codes. Thanks in advance
</p>
<code>
$ cat moveaverage2.pl
#!/usr/bin/perl -w
#use strict;
push(@Inc,'pwd');
#require Money::Finance;
use Money::Finance;
@values = ( 12,22,23,24,21,23,24,23,23,21,29,27,26,28 );
@mv = (0,10000);
$size = scalar(@values);
print "\n Values to work with = { @values } \n";
print " Number of values = $size \n";
#use strict;
# ----------------------------------------------------------------
# Calculate the average of the above function
# ----------------------------------------------------------------
my $cup = Money::Finance::new();
my $cup1 = new Money::Finance;
$ave =Money::Finance::getLastAverage(5,$size,@values);
print "\n Average of last 5 days = $ave \n";
Money::Finance::getMovingAve(5,$size,@values,@mv);
print "\n Moving Average with 5 days window = \n { @mv } \n";
$
$
$ cd Money
$
$
$ cat Finance.pm
package Money::Finance;
require Exporter;
@ISA = (Exporter);
@EXPORT = qw( new FutureValue PresentValue FVofAnnuity AnnuityOfFV
getLastAverage getMovingAve SetInterest);
#
# Globals, if any
#
local $defaultInterest = 5.0;
sub SetInterest($) {
my $rate = shift(@_);
$defaultInterest = $rate;
printf "\n \$defaultInterest = $rate";
}
# ------------------------------------------------------------------
# Notes:
# 1. The interest rate $r is given in a value of [0-100].
# 2. The $n given in the terms is the rate at which the interest
# is applied.
#
# ------------------------------------------------------------------
# ------------------------------------------------------------------
# Present value of an investment given
# fv - a future value
# r - rate per period
# n - number of period
# ------------------------------------------------------------------
sub FutureValue($$$) {
my ($pv,$r,$n) = @_;
my $fv = $pv * ((1 + ($r/100)) ** $n);
return $fv;
}
# ------------------------------------------------------------------
# Present value of an investment given
# fv - a future value
# r - rate per period
# n - number of period
# ------------------------------------------------------------------
sub PresentValue($$$) {
my $pv;
my ($fv,$r,$n) = @_;
$pv = $fv / ((1 + ($r/100)) ** $n);
return $pv;
}
# ------------------------------------------------------------------
# Get the future value of an annuity given
# mp - Monthly Payment of Annuity
# r - rate per period
# n - number of period
# ------------------------------------------------------------------
sub FVofAnnuity($$$) {
my $fv;
my $oneR;
my ($mp,$r,$n) = @_;
$oneR = ( 1 + $r) ** $n;
$fv = $mp * ( ($oneR - 1)/ $r);
return $fv;
}
# ------------------------------------------------------------------
# Get the annuity from the following bits of information
# r - rate per period
# n - number of period
# fv - Future Value
# ------------------------------------------------------------------
sub AnnuityOfFV($$$) {
my $mp; # mp - Monthly Payment of Annuity
my $oneR;
my ($fv,$r,$n) = @_;
$oneR = ( 1 + $r) ** $n;
$mp = $fv * ( $r/ ($oneR - 1));
return $mp;
}
# ------------------------------------------------------------------
# Get the average of the last "n" values in an array.
# ------------------------------------------------------------------
# The last $count number of elements from the array in @values
# The total number of elements in @values is in $number
#
sub getLastAverage($$@) {
my ($count, $number, @values) = @_;
my $i;
my $a = 0;
return 0 if ($count == 0);
for ($i = 0; $i< $count; $i++) {
$a += $values[$number - $i - 1];
}
return $a / $count;
}
# ------------------------------------------------------------------
# Get a moving average of the values.
# ------------------------------------------------------------------
# The window size is the first parameter, the number of items in the
# passed array is next. (This can easily be calculated within the
# function using the scalar() function, but the subroutine shown here
# is also being used to illustrate how to pass pointers.)
# The reference to the array of values is passed next, followed by a
# reference to the place the return values are to be stored.
#
sub getMovingAve($$\@\@) {
my ($count, $number, $values, $movingAve) = @_;
my $i;
my $a = 0;
my $v = 0;
return 0 if ($count == 0);
return -1 if ($count > $number);
return -2 if ($count < 2);
$$movingAve[0] = 0;
$$movingAve[$number - 1] = 0;
for ($i=0; $i<$count;$i++) {
$v = $$values[$i];
$a += $v / $count;
$$movingAve[$i] = 0;
}
for ($i=$count; $i<$number;$i++) {
$v = $$values[$i];
$a += $v / $count;
$v = $$values[$i - $count - 1];
$a -= $v / $count;
$$movingAve[$i] = $a;
}
return 0;
}
sub new {
my $this = {}; # Create anonymous hash, and #self points to it.
print "\n i am in new \n";
bless $this; # Connect the hash to the package Cocoa.
return $this; # Return the reference to the hash.
}
1;
$
</code>