Hi,
I missed the design by contract script? Could any of you guys mail it to me?
Thanks,
Maarten
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, February 21, 2001 9:10 PM
Subject: [REBOL] Re: Design by contract
> Gisle Dankel wrote:
> > Here's a Design By Contract script that I hacked together yesterday.
> > For those who don't know, Design By Contract is a software pattern used
to
> > enforce preconditions and postconditions of a function.
> > <snip>
>
> Thanks for this script. Tools for validating parameters are something
sadly
> lacking in Rebol as it stands today, and could do with being built into
the
> language. If Carl were to look at Eiffel he'd get an idea of the strength
> that such inbuilt capability would bring.
>
> As I try to write robust code, I typically find myself writing stuff like
> this little function:
>
> UpdateTuple: func [
> "Add/Subtracts M from the Nth part of a tuple"
> Tup [Tuple!] "Tuple to update"
> Nth [Integer!] "Nth part of tuple (leftmost is 1)"
> Val [Integer!] "Value to add/subtract from Tuple"
> ]
> [
> either all [(Nth > 0)
> not (Nth > Length? Tup)
> ] ; all
>
> [poke tup Nth ((pick tup Nth) + val)
>
> ] ;either true
> [
> CrashOut "UpdateTuple" "Nth is out of range"
> ] ; either false
> ]; func
>
>
> I give Rebol top marks for built-in documentation and parameter type
> specification. That's the first seven or so lines of the above function.
But
> the payload (a single line) is then embedded in another seven or so lines
of
> parameter checking. In Eiffel, the payload and the parameter checking
would
> be distinct.
>
> (Crashout is another little function of mine, not shown, that tries to
> shutdown gracefully while advising the user not to panic).
>
> Colin
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