Is it ever ok to store password in plain text in a php variable or php constant?

Question

As per question, is it safe to store passwords on php pages such as

$password = \'pa$$w0rd\';

If the users can\'t see it, it\'s safe, right

Answer 1

Sometimes it just has to be f.e. for a mail application where you can only login with the plain password and not with a hash. And if your application doesn't have security issues it should not affect you.