Re^3: why does push not default to $

push @a;

It is syntax which will compile, but it does generate a warning. Can you show an example of where this would be used?

use strict;
use warnings;
use diagnostics;
use Data::Dumper;

my @a = 1..3;
push @a;
print Dumper(\@a);

__END__
% ./728108.pl
Useless use of push with no values at ./728108.pl line 9 (#1)
    (W syntax) You used the push() or unshift() function with no argum
+ents
    apart from the array, like push(@x) or unshift(@foo). That won't
    usually have any effect on the array, so is completely useless. It
+'s
    possible in principle that push(@tied_array) could have some effec
+t
    if the array is tied to a class which implements a PUSH method. If
+ so,
    you can write it as push(@tied_array,()) to avoid this warning.

$VAR1 = [
          1,
          2,
          3
        ];
[download]

Comment on Re^3: why does push not default to $_? Download Code

Replies are listed 'Best First'.
Re^4: why does push not default to $_? by LanX (Saint) on Dec 04, 2008 at 21:56 UTC
Toolic, we perfectly know it's not implemented, we meditate WHY it's not implemented! Here a simple usecase: `for (1 .. 100) { next if $_%2; push @even; }` [download] Cheers Rolf UPDATE...PS: Thanx for the interesting link to Builtin functions defaulting to $_	[reply] [d/l]
Re^5: why does push not default to $_? by davidrw (Prior) on Dec 06, 2008 at 01:01 UTC
hmm. i think most people would write that usecase w/`grep` ... `push @even, grep { !($_%2) } 1 .. 100;` [download] (i guess there could be other stuff going on in the loop, but then it's more likely that `$_` would be named..	[reply] [d/l] [select]
Re^6: why does push not default to $_? by LanX (Saint) on Dec 06, 2008 at 01:11 UTC
Actually I was thinking the same thing, when I wrote it! : ) As I said, it's just a simple usecase. But if you want to push to several arrays in the same loop, it may be handy! Anyway it's not that I'm terribly missing one-parameter push, I just want to understand the underlying idea! And maybe be able to predict in which cases I can use default parameter without looking it up. Cheers Rolf	[reply]
Re^4: why does push not default to $_? by ikegami (Patriarch) on Dec 04, 2008 at 21:58 UTC
You wouldn't use such a construct. It just showed that your statement wasn't true. So whatever point you were trying to get across was even more lost to me.	[reply]