This is not a pipe

[TGI]

I have a challenge for the monastery! My wife is working on a painting that makes reference to Magritte's famous Treason of Images. She requested that I provide her with the phrase "This is not a pipe." in perl.

How many different ways can you come up with to say "This is not a pipe" in syntactically correct perl. While this could take the form of a JAPH, I think that something more along the lines of my suggestions below is what she wants.</>

I'll follow up with a post once she's made up her mind as to what she likes.

My ideas:

/[^|]/;  # Is this not a pipe?
/^[^|]$/;   # Is none of this a pipe?
$this neq 'a pipe'; # $this is not 'a pipe'

# Prints this is not a pipe.
$image = 'this is a pipe';
s/is /is not /g foreach ($image);
print $image;

Update! Fixed dumb mistake in examples, thanks to thor.

[hardburn]

! $this->isa("pipe")

Syntax is correct, though it will die in runtime because $this is not declared.

[jhourcle]

If you're worried about errors, I recommend instead:

! UNIVERSAL::isa($this, 'pipe')

Just in case there's a possibility that $this might be undef, or an unblessed scalar.

[hardburn]

For poetry, I'm not worried about it. Syntax correctness is all that matters, and putting UNIVERSAL in there just adds clutter.

[Revelation]

I think an easier way to prevent it from die-ing, would be to change that to:  !this->isa('pipe'); or  this->isa(!'pipe'); is another possibility. I agree the  Universal:: just add clutter.

[pijll]

-p '|'

[Tanktalus]

I like it. Although I think you meant:

!-p _

[pijll]

-p is a test operator, so your expression is more or less equivalent to a question: "Is _ (=this) not a pipe?".

At least in Unix, '|' is not a valid filename, so -p '|' will always be false: "Is '|' a pipe? No.". So the ASCII representation of a pipe, '|', is never a pipe itself, which is exactly what Magritte meant with his painting.

[Zaxo]

Or, taking "this" to be $_ as we do, -p and print, print q m n'est pas une pipem, $/; (yes, I mean that ;-)

[belg4mit]

It's too late now, but if perl had added a special syntax of m!! to indicate a negated match we could use m!\|!. As it is we have a modified form of one of sfink's suggestions: $_ !~ m/\|/.

Also, what about?

pipe(STDIN, STDOUT);
#Optional:
$|--, print STDOUT "This is not a pipe\n" ne <STDIN>;

[Tanktalus]

How abstract do you want it?

ref($this) ne 'Pipe';
ref($_) ne 'Pipe';     # $_ is a topicaliser, so is "this" - thus, "th
+is" == "$_"
! UNIVERSAL::can($this, 'smoke');
$_->can('smoke');

Perl 6 ok?

!.isa('Pipe');

Just wondering.

Update: Missed the ! on the perl6 code.

[idsfa]

$this = ! pipe $|,$|;

[kscaldef]

$SIG{PIPE} = sub { die "Ceci n'est pas une pipe" }

(This line has actually appeared in production code of mine)

[Hero Zzyzzx]

++ to you and your wife for referencing one of my absolute favorite paintings. There's another DaDa painting of a coffin sitting (literally sitting, posed like a person) on a fence or something that cracks me up everytime I see it.

[sfink]

  ! /^\|$/;
  $this !~ /^\|$/;
  ord($this) != 124;
  ord($this) != 0x7c;
  ord($this) != 0174;
  seek(THIS, 2, 0);
  `ls -l $this` !~ /^p/;
  ! -p _;
  return ! -p _;
  -p _ && die;
  die if -p _;
  return 1 unless -p _;
  use Test::More; isnt($this, 'pipe', 'Magritte check');
  $this ne 'a|';
  next unless /^(\w)\|$/; next if $1 eq 'a';
  open(my $fh, "a|"); while(<$fh>) { die if /\Q$this\E/; }

[thor]

Wouldn't /^|$/ match a single pipe on a line with nothing else, answering the question "is this a pipe only?"

[TGI]

Yep, you are right, I can't type! I meant:

/^[^|]$/;

[Roy Johnson]

It would match anything. It's an alternation, matching either start of string or end of string.

[thor]

Right you are. I was supposing that this was one of those situations where the regex characters were taken literally, like if you were to do m/^{/;.

[johndageek]

$pipe = "3.14159 + pe";
print "this is not a $pipe\n";

Eh! Why not?

[Adrade]

('|'?0:1)==0

die if '|'

$SIG{PIPE}={$p++};END{$p==0}

[gmpassos]

  
  if ( $this ne '|' ) {...}