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<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT face=Arial
color=#0000ff>Why not simply use something like this:-</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT face="Courier New"
color=#0000ff>rule "TaxCalc"<BR>
when<BR> $i : Invoice($st :
salesTax, $gst : gstRate, $sa : salesAmount, $id : importDuty, $gr :
govtRebate)<BR> then</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT face="Courier New"
color=#0000ff>
$i.setTotalTax(round($st + ($gst * $sa / 100) + $id – $gr,
2));</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT face=Arial><FONT
face="Courier New"><FONT color=#0000ff><SPAN class=373395905-03072009><SPAN
class=373395905-03072009>
update($i);</SPAN></SPAN><BR>end<BR></FONT></FONT></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT color=#0000ff><FONT
face=Arial>What do you gain by checking whether the Total Tax is different from
the value of the calculation? </FONT></FONT></SPAN><SPAN
class=373395905-03072009><FONT color=#0000ff><FONT face=Arial>I must be missing
something from your simplified example?!?</FONT></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT color=#0000ff><FONT
face=Arial></FONT></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT face=Arial
color=#0000ff>(I think, big disclaimer!!) you could achieve your requirement
using eval and a tax value function that uses a cache under the hood, much like
the following:-</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT face="Courier New"
color=#0000ff>rule "TaxCalc"<BR>
when<BR> $i : Invoice($tt :
totalTax, $st : salesTax, $gst : gstRate, $sa : salesAmount, $id : importDuty,
$gr : govtRebate)<BR>
eval(Invoice($tt != taxFunction($st, $gst, $sa, Sid, $gr))<BR>
then<BR>
$i.setTotalTax(taxFunction($st, $gst, $sa, Sid, $gr);</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT
face="Courier New"><FONT
color=#0000ff>
update($i);<BR>end<BR></FONT></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT face=Arial
color=#0000ff>Evals cannot be indexed so you take a performance
hit.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT
face="Courier New"><FONT color=#0000ff><FONT
face=Arial></FONT> </DIV></FONT></FONT></SPAN>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT color=#0000ff><FONT
face=Arial>With kind regards,</FONT></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT color=#0000ff><FONT
face=Arial></FONT></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=373395905-03072009><FONT color=#0000ff><FONT
face=Arial>Mike</FONT></DIV></FONT></SPAN><FONT color=#0000ff></FONT><FONT
color=#0000ff></FONT><BR>
<BLOCKQUOTE style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma><B>From:</B> rules-users-bounces@lists.jboss.org
[mailto:rules-users-bounces@lists.jboss.org] <B>On Behalf Of </B>Shabbir
Dhari<BR><B>Sent:</B> 03 July 2009 01:24<BR><B>To:</B>
rules-users@lists.jboss.org<BR><B>Subject:</B> [rules-users] Formula value
assginment in LHS<BR></FONT><BR></DIV>
<DIV></DIV>Dear all<BR><BR>We are developing a financial business application
that contains hundreds of business rules for validations and calculations. In
the calculation rules we change the value of attribute if values past in the
request is incorrect e.g. <BR><BR>rule "TaxCalc"<BR>
when<BR> $i :
Invoice()<BR> Invoice
(totalTax != (round(salesTax + (gstRate * salesAmount / 100) + importDuty –
govtRebate, 2)))<BR>
then<BR>
i.setTotalTax(round(salesTax + (gstRate * salesAmount / 100) + importDuty –
govtRebate, 2));<BR>end<BR><BR>The above code works perfectly fine. Only
problem is the perform calculation twice. What I was looking if possible I can
store calculated tax in a variable and simply assign variable to attribute if
rule condiation fails. Some thing like:<BR><BR>rule
"TaxCalc"<BR>
when<BR> $i : Invoice()
<BR> Invoice (totalTax != calTax :
(round(salesTax + (gstRate * salesAmount / 100)+ importDuty – govtRebate,
2)))<BR> then<BR>
i.setTotalTax(calTax);<BR> end<BR><BR>But this does not work
- shows system error at calculated value assignment. Is there any work
around?<BR><BR><BR>
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