Using Wolfgang's inline eval epression, I get the following error: "Cannot use this in a static context" when compiling the rule. I changed
"this" by "$c" and it works. I don't know why we are in a static context.

Strange. Most likely the compiler converts the inline eval to an eval CE, where you can't have "this".
I have occasionally used s.th. like
$foo : Foo( $bar : bar )
Bar( this == $bar )
which goaded me into thinking that this.method() should work in an inline eval.

Thanks for checking this, though!
-W

The rule that worked for me is:

Rule "Rule1"
when
$c:Cheese(type == "chedar", eval($c.existsInShop ("shopName"))

then
System.out.println("Rule1 is fired");
end

I attached a working test case. Change $c to "this" in rule's condition and you will see the error I mentioned.

Best,

2010/1/4 Wolfgang Laun <wolfgang.laun@gmail.com>

What you need is called "inline eval expression" (see the Drools Expert manual),
or an eval conditional element. The first one might be written as:

$c:Cheese(type == "chedar", eval( this.existsInShop("shopName") ) )

-W

On Mon, Jan 4, 2010 at 12:49 PM, orchid <maya.pollack@gmail.com> wrote:

Hi All,

I'm trying to call a class method from the LHS of a rule in the following
way:

public class Cheese{
private string type;
//setters and getters
public boolean existsInShop(String shop){
...
return true;
}
}

I would like to call the method "existsInShop" from a rule:

Rule "Rule1"
when
$c:Cheese(type == "chedar", existsInShop "shopName")
then
System.out.println("Rule1 is fired");
end

I get the compilation error: "no viable alternative at input "shopName" in
rule "Rule1" in pattern document". How can I call the method from the rule?

Thanks in advance.

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