Validate method/function parametershttp://search.cpan.org/dist/Params-Validate/
The Params::Validate module allows you to validate method or function
call parameters to an arbitrary level of specificity. At the simplest
level, it is capable of validating the required parameters were given
and that no unspecified additional parameters were passed in.
It is also capable of determining that a parameter is of a specific
type, that it is an object of a certain class hierarchy, that it
possesses certain methods, or applying validation callbacks to