Password complexity by number of character types

Password complexity by number of character types

A password requirement that specifies the number of character types, rather than the number of characters of a type, would be a nice addition. For example, if you specify that there must be 3 different character types, then "Password!" would be allowed and "Password" would not.

You could simulate this by setting requiring a special character, numeric character, and both upper and lower case letters by setting the number of password complexity requirements to one less than the total number, but I don't think that's sufficient. If you have other requirements such as disallowing palindromes, that requirement could be ignored by adding one of each character type.