[TIP] Sorting by ValueList and synchronized sorting
ambassador at fourthworld.com
Tue Jun 17 19:53:35 CDT 2008
J. Landman Gay wrote:
> Richard Gaskin wrote:
>> It's very handy, but a cognitive hurdle for me at first. I'd never seen
>> anything like it before.
> You probably blocked it. :)
Wow. So many posts I've overlooked. Must have had stuff in beta during
those threads. :)
Glad I took the time today, thought. You _can_ teach an old dog new
> Speaking of mental gymnastics, here's my favorite. I use it a lot. I
> didn't write it, it was written by Tony Root from HyperPro back in the
> day, and turned into a function by Paul Foraker:
> function whichOne var,fld1,fld2 -- from a handler by Tony Root
> -- Handles a case where you need to return one value if your key is
> empty, another if not.
> return (item offset(char 1 of (var = empty),"tf") of quote & fld1
> &","& fld2 & quote)
> end whichOne
> Paul says:
> "There's a great scripter working at Digital Pictures named Tony Root,
> who wrote a one-line boolean evaluator that I corrupted into a function.
> This handles the case where you need to return one value if your key is
> empty, another if not. For example, if the social security number field
> (var) is empty, then return "Please fill in your social security number"
> (fld1); otherwise, return "Now please fill in the form on the next
> page." (fld2). The elegant part (which Tony wrote) is getting the offset
> of char 1 of an expression that resolves to true or false, of "tf". Wish
> I'd thought of that. "
> You don't have to use it for just empty/not empty. With some
> adjustments, you can use it to choose between any two values.
In other languages that's called iff. Paul's/Tony's implementation is
very clever, but I believe it benchmarks a bit faster (and is easier to
read) when written as an if-else without the itemoffset and concatenation:
function whichOne pVal, pTrue, pFalse
if pVal is empty then return pTrue
else return pFalse
A more classic iff would evaluate any expression to true or false - this
one should handle empties as false as well:
function iff pExp, pTrue, pFalse
if pExp is true then return pTrue
else return pFalse
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