<br> Sergey,<br><br> Well, a "field constraint" must always involve a field. The decision to have it on the left side is to simplify syntax. For instance, if you want to write something like: "age between 30 and 40", you can do:
<br><br>Person( age > 30 && < 40 )<br><br> So you declare the field only once and can have as many expressions applied over it as you want, using restriction connectives (&& and ||).<br><br> Now, if your expression does not involve a field, then it is not a "field constraint". It may be an "inline-eval" (previously called predicate expression) for instance. And in this case, you use the "eval" keyword as showed in my previous example.
<br> Unfortunatelly, to avoid language ambiguities, we can't support arbitrary expressions without a markup keyword, and "eval" was the chosen keyword.<br><br> []s<br> Edson<br><br><div><span class="gmail_quote">
2007/8/10, Manukyan, Sergey <<a href="mailto:SManukyan@lear.com">SManukyan@lear.com</a>>:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div link="blue" vlink="blue" lang="EN-US">
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<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">Thanks Edson for workaround,</span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">IMHO that looks like a limitation to me,
is there a particular reason why left side should always be a field?</span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">-Sergey</span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<div>
<div style="text-align: center;" align="center"><font face="Times New Roman" size="3"><span style="font-size: 12pt;">
<hr align="center" size="2" width="100%">
</span></font></div>
<p><b><font face="Tahoma" size="2"><span style="font-size: 10pt; font-family: Tahoma; font-weight: bold;">From:</span></font></b><font face="Tahoma" size="2"><span style="font-size: 10pt; font-family: Tahoma;">
<a href="mailto:rules-users-bounces@lists.jboss.org" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">rules-users-bounces@lists.jboss.org</a>
[mailto:<a href="mailto:rules-users-bounces@lists.jboss.org" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">rules-users-bounces@lists.jboss.org</a>] <b><span style="font-weight: bold;">On
Behalf Of </span></b>Edson Tirelli<br>
<b><span style="font-weight: bold;">Sent:</span></b> Friday, August 10, 2007 11:58
AM<br>
<b><span style="font-weight: bold;">To:</span></b> Rules Users List<br>
<b><span style="font-weight: bold;">Subject:</span></b> Re: [rules-users] bug or
feature not yet implemented</span></font></p>
</div><div><span class="q" id="q_11450efd22b5835c_1">
<p><font face="Times New Roman" size="3"><span style="font-size: 12pt;"> </span></font></p>
<p style="margin-bottom: 12pt;"><font face="Times New Roman" size="3"><span style="font-size: 12pt;"><br>
Sergey,<br>
<br>
That is how it is supposed to work. A field constraint in Drools
always has a field at its left side. If you want arbitrary expression, just
embed it in an inline eval:<br>
<br>
S : Supplier( <br>
$sts :
supplierBusinessStatus.businessStatus,<br>
$csts : corporateSupplier.supplierBusinessStatus.businessStatus,
<br>
eval ( $sts != $csts ) <br>
) <br>
<br>
Although, for this specific case, it would be better (more
performatic) to simply write:<br>
<br>
S : Supplier(<br>
$sts :
supplierBusinessStatus.businessStatus,<br>
$csts : corporateSupplier.supplierBusinessStatus.businessStatus != $sts<br>
)<br>
<br>
[]s<br>
Edson</span></font></p>
<div>
<p><span><font face="Times New Roman" size="3"><span style="font-size: 12pt;">2007/8/10, Manukyan, Sergey <<a href="mailto:SManukyan@lear.com" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">SManukyan@lear.com
</a>>:</span></font></span></p>
<p><font face="Times New Roman" size="3"><span style="font-size: 12pt;"><br>
Folks,<br>
<br>
I found that drools 4.0GA doesn't recognize variables in the left side<br>
of operator expression<br>
<br>
Like this produces error:<br>
<br>
<br>
When<br>
S : Supplier(<br>
$sts :
supplierBusinessStatus.businessStatus ,<br>
$csts
:<br>
corporateSupplier.supplierBusinessStatus.businessStatus,<br>
$sts
!= $csts<br>
)<br>
Then<br>
...<br>
<br>
<br>
<br>
It tries to treat the $sts variable as a field of Supplier, instead <br>
understanding that it is a variable declared earlier,<br>
<br>
Please advise,<br>
<br>
Thanks,<br>
<br>
-Sergey<br>
<br>
<br>
<br>
<br>
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<p><font face="Times New Roman" size="3"><span style="font-size: 12pt;"><br>
<br clear="all">
<br>
-- <br>
Edson Tirelli<br>
Software Engineer - JBoss Rules Core Developer<br>
Office: +55 11 3529-6000<br>
Mobile: +55 11 9287-5646 <br>
JBoss, a division of Red Hat @ <a href="http://www.jboss.com" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">www.jboss.com</a>
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<br>_______________________________________________<br>rules-users mailing list<br><a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:rules-users@lists.jboss.org">rules-users@lists.jboss.org</a><br><a onclick="return top.js.OpenExtLink(window,event,this)" href="https://lists.jboss.org/mailman/listinfo/rules-users" target="_blank">
https://lists.jboss.org/mailman/listinfo/rules-users</a><br><br></blockquote></div><br><br clear="all"><br>-- <br> Edson Tirelli<br> Software Engineer - JBoss Rules Core Developer<br> Office: +55 11 3529-6000<br> Mobile: +55 11 9287-5646
<br> JBoss, a division of Red Hat @ <a href="http://www.jboss.com">www.jboss.com</a>