Is the 'my $x if 0' trick usable for static variable creation for Perls before 5.10?

In Perl before 5.10 there is no "state" declaration.

I've come across an example of creating static variables in these Perls: my $x if 0. The if 0 conditional makes the variable act like a static variable:

use strict; use warnings;
add() for 1..7;

sub add {
    my @arr = () if 0;

    push @arr, '+';
    print @arr, "\n";
}

prints:

+
++
+++
++++
+++++
++++++
+++++++

Is this behaviour consistent in all versions of Perl before 5.10?