I never quite understood why this is considered dangerous style. This is the old style of calling subroutines. If you do not predeclare you subs then you either have to &sub or sub() to not get a bareword error with use strict

When you call a subroutine like &sub I understand that you are passing the value of @_ to the sub or the equivalent of sub(@_). If you call sub(), you instead are passing a null list. But exactly how is passing @_ dangerous if the sub is not using any passed variables?

I think not knowing the following is more dangerous.

#!/usr/bin/perl -w
use strict;

my @test = ("one","two","three");
my $x    = "one";
my $y    = "two";
my $z    = "three";

test1($x,$y,$z);
print "$x\n$y\n$z\n\n";

test2($x,$y,$z);
print "$x\n$y\n$z\n";

test1(@test);
print join "\n", @test, "\n";

test2(@test);
print join "\n", @test, "\n";

sub test1 {
  my $x1 = shift;
  my $y1 = shift;
  my $z1 = shift;
  $_[0] = "test1: 1";
  $_[1] = "test1: 2";
  $_[2] = "test1: 3";
}

sub test2 {
  my ($x2,$y2,$z2) = @_;
  $_[0] = "test2: 1";
  $_[1] = "test2: 2";
  $_[2] = "test2: 3";
}

[download]
Output: 
one
two
three
 
test2: 1
test2: 2
test2: 3
one
two
three
 
test2: 1
test2: 2
test2: 3

[download]

Someone mind explaining this? In more detail than " '@_' is a local array, but its elements are aliases for the actual scalar paramters." What really gets me is how useing shift changes the behavior! Why?

zzSPECTREz

In reply to Re: Re (tilly) 2: Calling subroutine in a package from other perl sub. by zzspectrez
in thread Calling subroutine in a package from other perl sub. by Anonymous Monk

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