Wednesday, November 17, 2004

Running Dynamic Code with ExecScript

The Wiki has an interesting post on how to run dynamic code. While much of the post deals with using BINDEVENT, I just want to make a note on ExecScript.

This is one of the best additions to Visual FoxPro. In one application, we used to offer the ability for users to write their own validation rules (provided they knew how to write FoxPro expressions). Now, we take it even further: they can write their own full scripts.

Not only that - but we offer popular rule "templates" that users can build their existing rules from and use TEXTMERGE to fill in the appropriate values.

How so?

A rule table with a field for
Rule Description (cdesc)
Rule Script (mrule)
Rule Parameter (cparm)

The code that executes the rule does a

EXECSCRIPT(TEXTMERGE(mrule,"*PARM*",cParm))

The user only needs to fill in the Rule Description and the parameter - everything else is hidden from them.

Our templates start with easy to use templates like : This field must be filled in or here is a valid list of values to "Don't allow this entry unless today's date is Dec 31 and the user's name is XXXX".

By using rule templates, more advanced support staff can write rules that others then simply re-use by filling in the templates.

Previously, we had a bunch of FXP files lying around in folders where people had to learn the expression and the parameters. With ExecScript, you can put all of these into a library of functions and call them with Friendly names.

"Oh you need to send an email to a user?" Instead of making them learn how to write SENDEMAIL.PRG, they can call a function library call like

CallFunction("Send Email", "person@company.com", "Hi")

This is almost like going back to macros in Excel and Lotus days, but it becomes infinitely easier on the end user.

If you've never used ExecScript, try it out.

It's been in Visual FoxPro since VFP 7.

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