Hi,
I have a simple script with a subroutine that I pass scalar & array arguments
to,
#!/usr/bin/perl
use 5.01201;
use strict;
use warnings;
my $this_fn = "input.txt";
my @this_dr = qw(
/path/1
/path/2
);
my $this_rn = "recname";
my $this_ad = "1.2.3.4.";
sub modrec {
my %args = %{ shift @_ };
my $fn = $args{FN};
my $ar = $args{AR};
my $ad = $args{AD};
my @dr = @{$args{DR}};
return;
}
modrec (
{
FN=>$this_fn,
DR=>\@this_dr,
AR=>$this_rn,
AD=>$this_ad,
}
);
The script *executes* just fine.
But when I exec perlcritic on it
perlcritic --verbose 11 -harsh test.pl
Always unpack @_ first at line 15, near 'sub modrec {'.
Subroutines::RequireArgUnpacking (Severity: 4)
Subroutines that use `@_' directly instead of unpacking the
arguments to
local variables first have two major problems. First, they
are very hard
to read. If you're going to refer to your variables by
number instead of
by name, you may as well be writing assembler code! Second,
`@_'
contains aliases to the original variables! If you modify
the contents
of a `@_' entry, then you are modifying the variable
outside of your
subroutine. For example:
sub print_local_var_plus_one {
my ($var) = @_;
print ++$var;
}
sub print_var_plus_one {
print ++$_[0];
}
my $x = 2;
print_local_var_plus_one($x); # prints "3", $x is still 2
print_var_plus_one($x); # prints "3", $x is now 3 !
print $x; # prints "3"
This is spooky action-at-a-distance and is very hard to
debug if it's
not intentional and well-documented (like `chop' or
`chomp').
An exception is made for the usual delegation idiom
`$object->SUPER::something( @_ )'. Only `SUPER::' and
`NEXT::' are
recognized (though this is configurable) and the argument
list for the
delegate must consist only of `( @_ )'.
What's wrong with the way I'm unpacking the arguments passed to the subroutine,
my %args = %{ shift @_ };
Is there a different, recommended way?
AJ
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