Beefy Boxes and Bandwidth Generously Provided by pair Networks
Welcome to the Monastery
 
PerlMonks  

Re: return !!

by webfiend (Vicar)
on Mar 04, 2009 at 21:23 UTC ( #748325=note: print w/replies, xml ) Need Help??


in reply to return !!

It's doing a couple things, although only one of them is relevant to the execution of code:

  • As mentioned, it's returning 1 if there are any items in @value, and false otherwise.
  • It's wreaking havoc on Vim's syntax highlighting.
  • It's wreaking havoc on my own poor brain trying to parse "not not (scalar) @value".

I'd probably use a more explicit test, as the following example shows (lexical variables added for my own peace of mind):

use Modern::Perl; sub mean_test { my @value = @_; return !!@value; } sub nicer_test { my @values = @_; return scalar @values > 0; } say "Mean: Empty: ", mean_test(); say "Mean: One Item: ", mean_test("sweet!"); say "Mean: Two Items: ", mean_test("dude!", "sweet!"); say "Nicer: Empty: ", nicer_test(); say "Nicer: One Item: ", nicer_test("sweet!"); say "Nicer: Two Items: ", nicer_test("dude!", "sweet!");

It evaluates the same, as far as I can tell.

Mean: Empty:
Mean: One Item: 1
Mean: Two Items: 1
Nicer: Empty:
Nicer: One Item: 1
Nicer: Two Items: 1

Replies are listed 'Best First'.
Re^2: return !!
by massa (Hermit) on Mar 04, 2009 at 23:52 UTC
    The vim syntax highlighting thing can be fixed by putting a space between the bangs (! !@_).
    []s, HTH, Massa (κς,πμ,πλ)

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://748325]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others contemplating the Monastery: (3)
As of 2023-06-10 19:12 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    How often do you go to conferences?






    Results (39 votes). Check out past polls.

    Notices?