is used to enumerate the variables used in your code, ensuring that they exist, optionally setting default values if they do not, and possibly also validating data types. Placing a series of tags at the start of a page makes it easier to ensure that required variables exist, and that they are of the right type.
But what if you need to check for types not supported by ? What if you wanted to check for specific values or value ranges or value patterns?
In Blackstone we plan to enhance in several important ways:
1) Additional data types (including e-mail, url, ssn, usdate and eurodate).
2) Value ranges using specified minimum and maximum values.
3) Regular expression pattern matching for ultimate control.
Yet another example of one of the many infrequently discussed goodies in the works.