CODEWITHSUNDEEP
perl
jeberle
jeberle

Reputation: 758

Conditionally push to 1 of 2 arrays in Perl

Is there a better way to do this? I'm trying to build 2 arrays based on the value of a scalar:

my (@x, @y);
my $r = [$v1, $v2, $v3];
push @x, $r if $s eq 'YES';
push @y, $r if $s ne 'YES';

I tried using:

push $s eq 'YES' ? @x : @y, $r;

with and without parens, but no go.

Error is:

Type of arg 1 to push must be array (not null operation) at comp_report.pl line 79, near "$r;"

Upvotes: 6

Views: 1246

Answers (3)

robert_b_clarke
robert_b_clarke

Reputation: 1513

My preferred solution would be

if($s eq 'YES'){
   push @x, $r; 
else{
    push @y, $r;
}

Just a style thing. Using a ternary expression as the first argument to push looks messy to me, and I don't mind the extra lines. Personal taste I guess!

Upvotes: 1

ysth
ysth

Reputation: 98528

push requires its first parameter to be an actual array (at least before perl 5.14 and earlier - it may have changed), not an expression, so you need to:

push @{ $s eq 'YES' ? \@x : \@y}, $r;

Beginning in 5.14, builtins such as push experimentally can take arbitrary hard references, so this works:

push $s eq 'YES' ? \@x : \@y, $r;

Upvotes: 13

melpomene
melpomene

Reputation: 85907

push @{ $s eq 'YES' ? \@x : \@y }, $r;

push really wants to get an array as its first argument, but you can still select the target dynamically by using references.

Upvotes: 9

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