On 19 August 2011 15:17, Chris Richmond <span dir="ltr"><<a href="mailto:crichmond@referentia.com">crichmond@referentia.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
How do I fire a rule if an object with certain characterstics does not<br>
exists.<br>
<br>
For example my class Foo, if I have a rule:<br>
<br>
rule "Identify Foos with values"<br>
<br>
when<br>
Foo(stringProp=="blah", intProp==5)<br>
then<br>
System.err.println("A Foo was found!");<br>
end<br>
<br>
<br>
So how do I check for lack of existence of an object with certain<br>
characteristics<br>
<br>
I tried:<br>
rule "Flag missing Foos with values"<br>
<br>
when<br>
not(Foo(stringProp=="blah", intProp==5))<br>
then<br>
System.err.println("A proper foo does not exist");<br>
end<br></blockquote><div><br>That's the way to do it.<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
I also tried:<br>
rule "Flag missing Foos with values"<br>
<br>
when<br>
not(exists(Foo(stringProp=="blah", intProp==5)))<br>
then<br>
System.err.println("A proper foo does not exist");<br>
end<br></blockquote><div><br>Since not( Foo(...)) means "if no Foo(...) exists", the addition of "exists" is superfluous and generally considered bad style (even though some systems accept it to mean just "not".<br>
<br>-W<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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</blockquote></div><br>