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Re: RFC - Parameter Objects

by chromatic (Archbishop)
on May 14, 2003 at 18:29 UTC ( [id://258194]=note: print w/replies, xml ) Need Help??

in reply to RFC - Parameter Objects

Interesting. I've often thought that one failing of type checking parameter lists is that they can only tell you if a parameter fits in a type hierarchy somehow, not if the value of the parameter is actually valid.

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Re: Re: RFC - Parameter Objects
by Ovid (Cardinal) on May 14, 2003 at 18:42 UTC

    I actually got that idea from my CSV Database Validation program. For that, you can specify a regular expression as a "data type" for a database field. In thinking about this more, I realized that by arbitrarily passing in subroutines to validation routines, rather than try to hard-code methods that cover every possible case, I can let the programmer specify those in advance via sub references. It seems like a much more powerful system, the code is shorter, and you only build what you need.

    I do agree with you about the failings of parameter lists. Design by Contract seems to be one attempt to get around this weakness.


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