This is a pretty cute alternative:
sub empty ($) :lvalue {
if ($_[0]) {
require Carp;
if (eval { require PadWalker }) {
my $varname = PadWalker::var_name(1, \$_[0]);
Carp::croak("$varname is not empty, stopped");
}
Carp::croak("Variable is not empty, stopped");
}
$_[0];
}
# Asserts that $var1 is "empty" (i.e. the empty string, 0, or undef) a
+nd assigns $var2 as the new value.
empty $var1 = $var2;
# Can also be used like this to assert $var1 is empty without assignin
+g a new value.
empty $var1;
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