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stringperlequalitytruthiness

Is there a string in Perl that is equal to all other strings under eq?

I am running a string equality check like this:

if($myString eq "ExampleString")

Is there a value that myString could have which would cause execution to enter the if structure no matter what the string literal is?

Solution

  • Yes, with objects and overloaded operators:

    package AlwaysTrue {
  use overload 'eq' => sub { 1 },
               '""' => sub { ${+shift} };
  sub new {
    my ($class, $val) = @_;
    bless \$val => $class;
  }
}

my $foo = AlwaysTrue->new("foo");

say "foo is =$foo=";
say "foo eq bar" if $foo eq "bar";

    Output:

    foo is =foo=
foo eq bar

    However, "$foo" eq "bar" is false, as this compares the underlying string.