in reply to Reliably simulating 5.10 say()

Hello hlc, and welcome to the Monastery!

This is one case where prototypes are actually useful. From perlsub#Prototypes:

As the last character of a prototype, or just before a semicolon, a @ or a %, you can use _ in place of $: if this argument is not provided, $_ will be used instead.

Hence:

#! perl
use strict;
use warnings;

sub say (_)          # <-- ADD THIS
{
    print @_, "\n";
}

my @a = qw(1 2 3);

say for @a;

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Output:

 0:16 >perl 1151_SoPW.pl
1
2
3

 0:16 >

[download]

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

Replies are listed 'Best First'.
Re^2: Reliably simulating 5.10 say()
by LanX (Saint) on Feb 08, 2015 at 15:08 UTC
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[d/l]
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Re^2: Reliably simulating 5.10 say()
by choroba (Cardinal) on Feb 08, 2015 at 15:57 UTC
    Unfortunately, the _ prototype was added in 5.10 (check perl5100delta), the same version where say was added.
    لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ
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Re^2: Reliably simulating 5.10 say()
by ikegami (Patriarch) on Feb 08, 2015 at 15:41 UTC

    It actually behaves like 

    sub say (_)          # <-- ADD THIS
{
    local $\ = "\n";
    print @_;
}

    [download]
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[d/l]
Re^2: Reliably simulating 5.10 say()
by hlc (Initiate) on Feb 08, 2015 at 14:18 UTC
    Thanks, but that gives me the error: 
    Not enough arguments for main::say at a.pl line 10, near "say foreach 
+"
Malformed prototype for main::say: _ at a.pl line 13.

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[reply]
[d/l]
      Perhaps it is a relatively new feature. Which version of Perl are you running?

      The same code works for me in Perl 5.14.

      Update: I did not see it before I posted the above, but several people have responded below that it is a feature that was introduced in version 5.10.

      Je suis Charlie.
[reply]
      It works perfectly for me. Please show the exact code that you tested and gave this error.

      Je suis Charlie.
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        #!/usr/bin/env perl                                                   
+          
                                                                      
+          
use strict;                                                           
+          
use warnings;                                                         
+          
                                                                      
+          
sub say (_) {                                                         
+          
    print @_, "\n";                                                   
}                                                                     
+          
                                                                      
+          
my @a = qw(1 2 3);                                                    
+          
                                                                      
+          
# using implicit $_ does not work:                                    
+          
say foreach (@a);                                                     
+          
                                                                      
+          
# ...and of course explicit $_ works.                                 
+          
say $_ foreach (@a);                                                  
+          
                                                                      
+          
# works:                                                              
+          
say "uncle bob";

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        The error for above: 
        Illegal character in prototype for main::say : _ at a.pl line 6.
Not enough arguments for main::say at a.pl line 13, near "say foreach 
+"
Malformed prototype for main::say: _ at a.pl line 16.

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[d/l]
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