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.

    Cheers,
    Ovid

    New address of my CGI Course.
    Silence is Evil (feel free to copy and distribute widely - note copyright text)

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