Thursday, November 1, 2001

LotusScript’s Evaluate command

PROGRAMMING POWER

By Tony Patton

The basic premise of Evaluate is allowing the use of @Functions within LotusScript. Although LotusScript is very poweful, Domino developers often find themselves clamoring for their favorite function in certain situations.

Syntax

Evaluate accepts one parameter and returns a Variant object. The parameter contains the @Function code, and the Variant contains the results of executing the specified @Function. Here is the syntax from Lotus Help.

Evaluate ( "macro" [, object] )

The macro is a String representation of the Lotus @Formula to be evaluated. It may be a variable or constant. The value had to be a constant in pre-R5 versions, but this was corrected in R5.

The second parameter is optional; it is used to signify the name of a product object (if Lotus is not used). I have never seen this used, so it's not covered in this article.

Return value

As previously stated, the return value is returned in the form of a Variant object. The return value of the actual @Formula is text, but the Evaluate function returns a Variant. The first value in the Variant (zero) contains the return value, and an empty return value signals nothing returned from the @Formula or an error.

In action

Evaluate usage will depend on your needs and Notes version, but here are a few examples showing Evalute in action.

I always liked the @Adjust formula. It allows easy manipulation of time-date values. The individual components of a time-date may be incremented/decremented accordingly. Here is its syntax from Note help.

        @Adjust( dateToAdjust ; years ; months ; days ; hours ; minutes ; seconds ; [ DST] )
        Parameters
        dateToAdjust Time-date. The single time-date value to be manipulated.
        years - Number. The number of years to increment by.
        months - Number. The number of months to increment by.
        days - Number. The number of days to increment by.
        hours - Number. The number of hours to increment by.
        minutes - Number. The number of minutes to increment by.
        seconds - Number. The number of seconds to increment by.
        dst - Keyword. Optional. Specify [InLocalTime] to further adjust the time for daylight savings if the   adjustment crosses the boundary and daylight savings is in effect. Specify [InGMT] or omit this         parameter to not further adjust the time for daylight savings. The adjustment is such that adding or    subtracting in day increments yields the same time in the new day.

Now, @Adjust is used in LotusScript. A LotusScript function is used to take advantage of it whenever needed. The function allows the year, month, and/or day portion of a date-time value to be manipulated.

Consider this first example.

Function AdjustDate ( pYear As Long, pMonth As Long, pDay As Long, pDate As Variant ) As Variant
 Dim temp As String
 temp = |@Adjust([| & Cstr(pdate) & |];| & Cstr(pYear) & |;| & Cstr(pMonth) & |;| & Cstr(pDay) &|;0;0;0)|
 AdjustDate = Evalute ( temp )
End Function