> when is an array in perl declared with [] instead of ()? Using the [ ] delimiters you are creating a *reference* to an array. (Think of a reference as the memory address where the array is stored). So
my $foo = [1,2,3]; is equivalent to the following, because given an array the \ gets the reference to that array: my @bar = (1,2,3); my $foo = \@bar; > why aren't arrays created the same way when being passed as parameters to functions (when signatures are being used)? The signatures aren't doing much other than automatically assigning parts of @_ to variables declared in the signature. (For more detail, see https://www.effectiveperlprogramming.com/2015/04/use-v5-20-subroutine-signatures/ ) In the code you provided: sub reply_multi ( $xmpp_o, $rcpts, $msg ) { the argument $rcpts is expected to be a *reference* to an array, rather than an array. It's a reference because in this line: foreach my $rcpt (@$rcpts) { @$rcpts is "dereferencing" to get the array. > Parentheses should take precendence, shouldn't they? They don't. The array is flattened into the list of arguments which means that: reply_multi( \$daemon{xmpp_o}, \($adminuser{fromJID}, $fromJID), "blah" ); becomes reply_multi( \$daemon{xmpp_o}, \$adminuser{fromJID}, \$fromJID, "blah" ); resulting in the error: "Too many arguments for subroutine 'main::reply_multi' (got 4; expected 3)". A On Sat, Jan 13, 2024 at 5:03 PM hw <h...@adminart.net> wrote: > On Sat, 2024-01-13 at 15:00 +0000, Andrew Solomon wrote: > > I think the line: > > > > reply_multi( \$daemon{xmpp_o}, \($adminuser{fromJID}, $fromJID), "blah" > ); > > > > should have \(...) replaced with [ ... ] : > > > > reply_multi( \$daemon{xmpp_o}, [$adminuser{fromJID}, $fromJID], "blah" ); > > > > because > > > > \('foo', 'bar') > > > > evaluates to > > > > (\'foo', \'bar') > > > > Does that clarify this for you? > > Not really ... I vaguely thought that [] might do the trick, but > since when is an array in perl declared with [] instead of ()? You > can also do > > > foreach my $foo ('bar', 'baz') { > print "$foo\n"; > } > > > since foreach takes arrays. So why aren't arrays created the same way > when being passed as parameters to functions (when signatures are > being used)? > > Somehow I don't remember what [] exactly do there :/ If that's like > > > foreach my $foo (@['bar', 'baz']) > > > I'd guess I remember correctly and it would kinda make sense ... > > But still ... Parentheses should take precendence, shouldn't they? > > > > Andrew > > > > On Sat, Jan 13, 2024 at 2:51 PM hw <h...@adminart.net> wrote: > > > > > Hi, > > > > > > how do I pass an array that is created on the fly as one parameter of > > > a function? > > > > > > Example: > > > > > > > > > use feature 'signatures'; > > > no warnings 'experimental::signatures'; > > > > > > sub reply_multi ( $xmpp_o, $rcpts, $msg ) { > > > foreach my $rcpt (@$rcpts) { > > > $$xmpp_o->MessageSend( type => 'chat', to => $rcpt, body => > $msg ); > > > } > > > > > > return; > > > } > > > > > > reply_multi( \$daemon{xmpp_o}, \($adminuser{fromJID}, $fromJID), > "blah" ); > > > > > > > > > This gives me an error at runtime: "Too many arguments for subroutine > > > 'main::reply_multi' (got 4; expected 3)". > > > > > > Yeah, sure, ok, but is that even right? Or is signatures too > > > experimental to handel that yet? Or how do I do what I want here? > > > > > > > > > -- > > > To unsubscribe, e-mail: beginners-unsubscr...@perl.org > > > For additional commands, e-mail: beginners-h...@perl.org > > > http://learn.perl.org/ > > > > > > > > > > > > > > -- > To unsubscribe, e-mail: beginners-unsubscr...@perl.org > For additional commands, e-mail: beginners-h...@perl.org > http://learn.perl.org/ > > >
