pass by reference

[Michele Dondi]

Fine. Everyone is telling you that it's not a good practice
and you're not going to convince anyone that it is a good practice.

Oh, C'mon! While I NEVER do that myself (guess I have a penchant for
fp - while never having dove into it) Perl is already so
side-effectful that it shouldn't matter, if one really knows what
she's doing.


Michele

 

[Michele Dondi]

I don't like the $_[0] method, because it doesn't give me a chance to
name my variables.... I prefer names, not numbers, thank you!

Wait for Perl 6. Or play with pugs already! ;-)


Michele

 

[Michele Dondi]

$_ is a name, just not a pronounceable one!

In English, it's "it".


Michele

 

[anno4000]

The following code snippet shows how I do "pass by reference" in
Perl. It works fine, but I'm wondering... is there a less verbose way
to do this?

[...]

Do you really want side effects ?
Passing by reference does this.
Guess this is too simple to make that decision.

sub squareMe($) {
my ($arg) = @_;
$arg *= $arg;
}

my $n=7;
$n = squareMe $n; # no side effects
I hate it when my variables get changed somewhere else and I have to
track it down for debugging!

That raises the question why you are using the mutator "*=" at all. It
doesn't do anything useful.

sub square_me {
my $arg = shift;
$arg*$arg;
}

would be exactly equivalent, as would be

sub square_me { $_[0]*$_[0] }

Anno

 

[J. Gleixner]

In English.pm it's "$ARG" ...

Shouldn't that be Pirates.pm?

 

[Billy Patton]

The following code snippet shows how I do "pass by reference" in
Perl. It works fine, but I'm wondering... is there a less verbose way
to do this?

[...]

Do you really want side effects ?
Passing by reference does this.
Guess this is too simple to make that decision.

sub squareMe($) {
my ($arg) = @_;
$arg *= $arg;
}

my $n=7;
$n = squareMe $n; # no side effects
I hate it when my variables get changed somewhere else and I have to
track it down for debugging!

That raises the question why you are using the mutator "*=" at all. It
doesn't do anything useful.

sub square_me {
my $arg = shift;
$arg*$arg;
}

would be exactly equivalent, as would be

sub square_me { $_[0]*$_[0] }

Anno

The beauty of perl "Always more than one way to skin a cat"

 

[Michele Dondi]

In English.pm it's "$ARG" ...

No, that's "useless quoting of variables"...


Michele

 

[Michele Dondi]

No, that's "useless quoting of variables"...

I forgot to add


Michele

 

[Clenna Lumina]

In English, it's "it".

Yes, in the context of for loops*, map, and such, from what I understand
that's exactly what "it" is

* Though it doesn't seem to be the came of a while loop onless you're
reading a handle (file, pipe, socket, etc) using the <HANDLE> systax
that sets the line to $_ each time around.

 

[Clenna Lumina]

The following code snippet shows how I do "pass by reference" in
Perl. It works fine, but I'm wondering... is there a less verbose
way to do this?

[...]

Do you really want side effects ?
Passing by reference does this.
Guess this is too simple to make that decision.

sub squareMe($) {
my ($arg) = @_;
$arg *= $arg;
}

my $n=7;
$n = squareMe $n; # no side effects
I hate it when my variables get changed somewhere else and I have to
track it down for debugging!

That raises the question why you are using the mutator "*=" at all. It
doesn't do anything useful.

sub square_me {
my $arg = shift;
$arg*$arg;
}

would be exactly equivalent, as would be

sub square_me { $_[0]*$_[0] }

Anno

Or do ya one better for a variable amount of arguments and
simultaneously increasing it's usefulness:

sub square_me { wantarray ? map { $_*$_ } @_ : $_[0]*$_[0]; }

my $sq = square_me 5;
print $sq, "\n";

my @squares = square_me 3, 7, 12;
print join(', ', @squares);

Output:

25
9, 49, 144

This allows it to be used in both scalar and list context, and of course
can be expanded for more useful algorithms of course.

 

[Clenna Lumina]

Larry wrote:
The following code snippet shows how I do "pass by reference" in
Perl. It works fine, but I'm wondering... is there a less verbose
way to do this?
[...]

Do you really want side effects ?
Passing by reference does this.
Guess this is too simple to make that decision.

sub squareMe($) {
my ($arg) = @_;
$arg *= $arg;
}

my $n=7;
$n = squareMe $n; # no side effects
I hate it when my variables get changed somewhere else and I have to
track it down for debugging!

That raises the question why you are using the mutator "*=" at all.
It doesn't do anything useful.

sub square_me {
my $arg = shift;
$arg*$arg;
}

would be exactly equivalent, as would be

sub square_me { $_[0]*$_[0] }

Anno

The beauty of perl "Always more than one way to skin a cat"

Just how many ways do you need to skin a cat yeeesh

(Seriously though, it's one the things I really love about Perl)

 

[Michele Dondi]

Yes, in the context of for loops*, map, and such, from what I understand
that's exactly what "it" is

* Though it doesn't seem to be the came of a while loop onless you're
reading a handle (file, pipe, socket, etc) using the <HANDLE> systax
that sets the line to $_ each time around.

It's more or less still "it", the rationale being that a natural
language concept like a pronoun can fit nicely in the model of a
programming one, but it won't map just *exactly*: Perl *resembles*
English in some points, but obviously it is *not* English:

: If I convert a program into English, I don't get Shakespeare, but
: Cobol. A subset of English fit for morons and guaranteed not to make
: use of its expressive powers.
: - David Kastrup in comp.text.tex, "Re: pdflatex or dvipdf ?"


Michele

 

[Billy Patton]

Larry wrote:
The following code snippet shows how I do "pass by reference" in
Perl. It works fine, but I'm wondering... is there a less verbose
way to do this?
[...]

Do you really want side effects ?
Passing by reference does this.
Guess this is too simple to make that decision.

sub squareMe($) {
my ($arg) = @_;
$arg *= $arg;
}

my $n=7;
$n = squareMe $n; # no side effects
I hate it when my variables get changed somewhere else and I have to
track it down for debugging!
That raises the question why you are using the mutator "*=" at all.
It doesn't do anything useful.

sub square_me {
my $arg = shift;
$arg*$arg;
}

would be exactly equivalent, as would be

sub square_me { $_[0]*$_[0] }

Anno

The beauty of perl "Always more than one way to skin a cat"

Just how many ways do you need to skin a cat yeeesh

(Seriously though, it's one the things I really love about Perl)

Depends on the cat and your skinning tool

 

[Clenna Lumina]

(e-mail address removed)-berlin.de wrote:
Larry wrote:
The following code snippet shows how I do "pass by reference" in
Perl. It works fine, but I'm wondering... is there a less
verbose way to do this?
[...]

Do you really want side effects ?
Passing by reference does this.
Guess this is too simple to make that decision.

sub squareMe($) {
my ($arg) = @_;
$arg *= $arg;
}

my $n=7;
$n = squareMe $n; # no side effects
I hate it when my variables get changed somewhere else and I have
to track it down for debugging!
That raises the question why you are using the mutator "*=" at all.
It doesn't do anything useful.

sub square_me {
my $arg = shift;
$arg*$arg;
}

would be exactly equivalent, as would be

sub square_me { $_[0]*$_[0] }

Anno
The beauty of perl "Always more than one way to skin a cat"

Just how many ways do you need to skin a cat yeeesh

(Seriously though, it's one the things I really love about Perl)

Depends on the cat and your skinning tool

Very true.

P.S. Please stay away from my cat.