An idea about calculated fields

[tlyon]

Wouldn't it be great if we could use a function for a calculated field? Just pass the necessary values/parameters to the function and return a value?

Drool.

Is there any mechanism now in place that even remotely approximates such a thing?

Tom Lyon

[tlyon]

RE: An idea about calculated fields

I'm not believing what I see. It works. At least for the test which I have just now conducted. I put:

FunctionTest(10000) as the expression in a calc field.

FunctionTest consists of:

function FunctionTest as N(seed as N)
FunctionTest = rand() * seed
end function

Again, it works. I am going to try a longer, more complicated example with more XBasic and see if this isn't just a quirk.

Tom Lyon

[Tom Cone Jr]

RE: An idea about calculated fields

Tom,

I use 'built in' functions in calc field expressions all the time, and so do you, I'd wager. Things like str(), and trim(), and so on... I'm glad to see that user defined functions seem to work the same way. One key advantage of this is that if you need to tweak the function one day, you do it, and all the calc fields that refer to it are, in a sense, updated, too. -- tom

[tlyon]

RE: An idea about calculated fields

Built-ins, yes, I have used to a great extent. However, I have just discovered that custom functions will work as well. There is a very interesting aspect to using the latter, I have found. If you have a calc field in a browse, every record in the browse is calculated and stored before the form is opened. With this method, the fields are calculated when fetched. This could be a boon in some cases, but not all. The beauty of it is you can use your normal XBasic commands. No more confusing if() functions.
The ability to create some very sophisticated calculated fields will help me in many ways.

Ira got me started on functions. Now I can't stop :)

Tom Lyon

[csda1]

RE: An idea about calculated fields

Hi Tom,

What made you think that Custom Functions wouldn't work? I've mentioned using them in calc fields (or anywhere you have an expression) many times before. And they can do other things at the time of evaluation (e.g. mark a record as printed for example), although you must be careful, because the expression is often evaluated several times by Alpha 5 whenever the expression that uses the function is actually invoked.

But the drawback is a user-defined-function call takes longer to run than a built-in function. When run on many records or in a loop, this can be significant.

Regards,

Ira J. Perlow
Computer Systems Design & Associates
[email protected]

[tlyon]

RE: An idea about calculated fields

You are correct in regards to time execution time. However, for certain forms that are used, say, once or twice a day, I have found it to be quite helpful. Of course, one could redesign a table to eliminate the need for such things, but when you need something quick and dirty to get the job done, it's come in handy.

I don't know why I assumed custom functions would not work in calc fields. It would seem, on reflection, that a function is a function is a function. And luckily, Alpha Software thought the same.

I love functions.

Tom Lyon