Re: Assign multiple scalars the same value

[Tanktalus]

in reply to Assign multiple scalars the same value

my ($a, $b, $c) = ('TRUE') x 3;

Always many ways of doing it ;-)

[dimar]

Jeepers! the 'x' operator works on lists too!?

Looks like time to refactor out all ...

my ($a,$b,$c) = map {'TRUE'}(0 .. 2);

[Aristotle]

Yep, it does. Note the difference between these, though:

$,= " "; $\ = "\n";
print( map { int rand 10 } 0 .. 6 );
print( ( int rand 10 ) x 7 );

The x operator only evaluates the list expression once. So you can't always substitute one for the other.

[Limbic~Region]

scooterm,
Not only that, but if the what the list contains is a reference, the reference is replicated as well. The first useful application I remember seeing of this is in tye's Algorithm::Loops. I found a useful variation that looked a little something like:

my @signal = qw(ABRT STOP TERM INT);
@SIG{ @signal } = (sub { kill 9, $pid; exit }) x @signal;

Incidently, diotalevi makes a good point concerning ensuring that you have the same number of things on both sides of the assignment which is not an issue in my example.

[diotalevi]

This solution is less good than simply assigning the value to each variable separately in my $a = my $b = my $c = 'TRUE' because it avoids having to count how many variables you have. In your code, if you got the number wrong then the trailing variables will be left undefined which is far and away from the intent to leave them with a true value. You're making it easy to write in a bug later.

[xdg]

Good point. One could always do this:

use Want 'howmany';
my ($a, $b, $c) = &{ sub{ (1) x howmany } };

Not sure if that's shorter/better than other solutions (plus requires Want), but it's another way of keeping the number of variables in sync.