# 5.14.0 or later
$ perl -E 'my ($x, $y) = (0, "fallback"); $x = length $x ? $x : $y; say $x'
0

$ perl -E 'my ($x, $y) = ("0", "fallback"); $x = length $x ? $x : $y; say $x'
0

$ perl -E 'my ($x, $y) = ("", "fallback"); $x = length $x ? $x : $y; say $x'
fallback

$ perl -E 'my ($x, $y) = (undef, "fallback"); $x = length $x ? $x : $y; say $x'
fallback

# 5.12.0 or earlier
$ perl -E 'my ($x, $y) = (0, "fallback"); $x = (defined $x && length $x) ? $x : $y; say $x'
0

$ perl -E 'my ($x, $y) = ("0", "fallback"); $x = (defined $x && length $x) ? $x : $y; say $x'
0

$ perl -E 'my ($x, $y) = ("", "fallback"); $x = (defined $x && length $x) ? $x : $y; say $x'
fallback

$ perl -E 'my ($x, $y) = (undef, "fallback"); $x = (defined $x && length $x) ? $x : $y; say $x'
fallback

# Probably not what was intended
$ perl -E 'my ($x, $y) = ("0", "fallback"); $x ||= $y; say $x'
fallback

$ perl -E 'my ($x, $y) = ("", "fallback"); $x //= $y; say "<$x>"'
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