I'm validating input to a function, via named parameters, that inserts stuff into a database using DBI. For each parameter passed (say %param), I run it through a bunch of validation routines, massage it and spit out what, if all tests pass, should be inserted into the database...my validation routines for each parameter might be different and are stored as references in a hash. ie.

%validationHash = (
  "name" => {
    "regexp" => "string",
    "status" => "required",
    "outputsub" => \&massage;
  },
  "phone" => {
    "regexp" => "phone",
    "status" => "optional",
    "outputsub" => \&mungephonenum,
  },
);
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then I iterate over the keys in the hash (ie.$param{'name'}) (thereby ignoring any parameters passed that I don't care about), make sure it is defined if $validationHash{"name"}{"status"} eq "required" otherwise return undef etc. then make sure that it looks like a "string" with a routine that runs a regexp match and finally, return a value $validationHash{'name'}{'outputsub'}->($param{'name'}) as what should be inserted into the database.

Needless to say, I would love to hear about nice ways of validating input and even better, ways of constructing SQL statements given such input (I'm considering using DBIx::Recordset for the latter, but I've done enough work already that I might have to come back to it at another time).

BTW, the first solution given worked very well and I am using it successfully, thanks.
-Adi