Re^2: is this script secured enough from internet attacks

Perl 4 is dead. An ampersand in front of the function name does something very different in Perl 5 than it did in Perl 4, and usually you do not want that. Get rid of the ampersands.

Could you explain you comment about ampersands?

I have never coded in perl 4, but have used perl5 since 1997 on AIX (perl5.00404).

I distinguish between the subroutines that I have written and those that are part of a "use Module" from core or CPAN.

For example ( without all the code needed to actually work ):

use BerkeleyDB;  # CPAN module
use Common;      # My module

my $cursor = $db->db_cursor();                 # BerkeleyDB function
my $var    = &BD_Read($FH,$db,\$key,\$data);   # my subroutine BD_Read
[download]

I use this to help me distinguish between the source of the code.

Is there something wrong with my personal preference?

"Well done is better than well said." - Benjamin Franklin

Comment on Re^2: is this script secured enough from internet attacks Download Code

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Re^3: is this script secured enough from internet attacks by Limbic~Region (Chancellor) on Jun 10, 2011 at 18:37 UTC
flexvault, Read perlsub. `NAME(LIST); # & is optional with parentheses. NAME LIST; # Parentheses optional if predeclared/imported. &NAME(LIST); # Circumvent prototypes. &NAME; # Makes current @_ visible to called subroutine.` [download] Unless I am creating a reference to a sub (`my $subref = \&somesub;`), I almost never even think about using & with a sub name purely out of habit. The rare exception is when I am using `goto &somesub;` which @_ gets inherited. Cheers - L~R	[reply] [d/l] [select]
Re^3: is this script secured enough from internet attacks (&) by tye (Sage) on Jun 10, 2011 at 20:58 UTC
My experience is that you will mostly find rather strong reactions against using `&` when calling subroutines. However, the only problem with doing so beside over-zealous style-related reactions is that doing so also disables function prototypes. But, if you use function prototypes, you are also likely to get over-zealous reactions against doing such. So the real problems with using `&` are minimal or none. On the other side, what are the arguments in favor of using `&` ? There is the style argument that you gave. The `&` provides a visual cue that the function being invoked is certainly not a Perl built-in (it can't be). You can also make the style choice of using `&` on functions local to the current package and then not using `&` on functions imported from other modules. It is funny that people who love Perl, including the ugly sigils it pollutes the code with seem to hate the red-headed step-child Perl sigil of `&`, despite it offering the same style / visual benefits. But is there a benefit to using `&` other than style? Actually, there is. `#!/usr/bin/perl -w use strict; sub dump { require Data::Dumper; my $d= Data::Dumper->new( \@_ ) # The defaults are "all wrong": ->Indent(1)->Useqq(1)->Terse(1)->Sortkeys(1); return $d->Dump(); } print &dump( @ARGV );` [download] Since I didn't use a function prototype, surely I can just drop that "ugly" `&` and nothing changes. Note that the above problem doesn't happen for: `use A::Module qw< dump >; print dump( @ARGV );` [download] actually reinforcing the above style choice of only using `&` on subs local to (defined in, not imported to) the current package. I solve that problem by capitalizing all of my subroutine names. Of course, that just leads to me learning that there are quite a few people with rather violent style-based reactions against the dreaded and ugly CamelCase. But at least I get to pick which group grumbles at my code. ;) - tye	[reply] [d/l] [select]
Re^4: is this script secured enough from internet attacks (&) by Jenda (Abbot) on Jun 11, 2011 at 01:13 UTC
The problem with the ampersand is that most people expect that just like `&foo(1,2,3)` behaves the same as `foo(1,2,3)` `&foo;` behaves the same as `foo;` and it does not. It's too easy to remove all your arguments and having the subroutine fiddle with your @_ instead of getting no arguments. Jenda Enoch was right! Enjoy the last years of Rome.	[reply] [d/l] [select]
Re^5: is this script secured enough from internet attacks (&) by tye (Sage) on Jun 11, 2011 at 01:32 UTC
Actually, people who like cues to make their subroutine calls easier to identify visually are unlikely to run into that problem, even if they weren't aware of the potential. Even though I don't use `&`, I never leave off the parens when calling a user-defined function (or method) with no arguments; the lack of parens screams "not a subroutine call" too loudly to me. I only rarely even make an exception for constants (and I wouldn't use `&` for constants, personally). In any case, it is a trivial matter of informing the coder of that one simple fact to prevent that problem. - tye	[reply] [d/l] [select]
Re^3: is this script secured enough from internet attacks by Anonymous Monk on Jun 10, 2011 at 17:41 UTC
Is there something wrong with my personal preference? Its like wearing a tutu when you're not a ballerina ? :)	[reply]
Re^3: is this script secured enough from internet attacks by ikegami (Patriarch) on Jun 10, 2011 at 18:28 UTC
Is there something wrong with my personal preference? Yes. You said you would add a "`&`" to `$db->db_cursor()` if it was your own module, but it's impossible to do so.	[reply] [d/l] [select]