Question

以下是dsl的一些简单示例。让我们在WHEN块中说出真实的是＆＃34; city ==＆＃34; NY＆＃34;＆＃34;，有没有办法知道，然后＆＃34;然后＆＃34;阻止，哪种情况属实？

rule "First Promotion"
    when
        m : Promotion( city == "NY" || products == "SCHERP_S" || assignedProduct == "SCHERP_XL" )
    then
**//Here I have to know what was true in WHEN block. For example city value is NY.**
end

谢谢你！

Answer 1

技术上不是因为你使用了||，而是可以做多个规则

rule "First Promotion_city"
    when
        m : Promotion( city == "NY")
    then
end

rule "First Promotion_products"
    when
        m : Promotion( products == "SCHERP_S")
    then
end

rule "First Promotion_assigned"
    when
        m : Promotion( assignedProduct == "SCHERP_XL")
    then
end

Answer 2

简单地拆分规则会产生令人不快的副作用，即要求条件的乘法（或使用规则扩展）和后果的乘法，以及代码重复的所有缺点。

更好的解决方案是使用真值推理为更加重要的值创建合适的表示。

让我们有一个

class Reason {
    Promotion promo;
    String field;
    String value; 
    Public( Promotion promo, String field, String value ){...}
    //...
}

这可以用于使用如下规则来记录析取的原因：

rule "First Promotion_city"
when
    m : Promotion( $city: city == "NY" || "LA" )
then
    insertLogical( new Reason( m, "city", $city ) );
end

我添加了LA以显示可以使用一个规则处理多个值。

实际规则变为

rule "First Promotion"
when
    m : Promotion(  )
    r: Reason( promo == m )
then
    //... access r for details
end

对于多个值，析取可能为真，因此您可能会插入多个Reason事实。我不能就此提出建议，因为我不知道“整体情况”。

显然，RHS的区别需要逻辑来决定什么是真的。但在Q中，没有任何迹象表明“必须知道什么是真的”。当然，获取原始事实是直截了当的可能性。但是，将. sysuse auto, clear (1978 Automobile Data) . d Contains data from C:\Program Files\Stata10\ado\base/a/auto.dta obs: 74 1978 Automobile Data vars: 12 13 Apr 2007 17:45 size: 3,478 (99.9% of memory free) (_dta has notes) -------------------------------------------------------------------------------------- storage display value variable name type format label variable label -------------------------------------------------------------------------------------- make str18 %-18s Make and Model price int %8.0gc Price mpg int %8.0g Mileage (mpg) rep78 int %8.0g Repair Record 1978 headroom float %6.1f Headroom (in.) trunk int %8.0g Trunk space (cu. ft.) weight int %8.0gc Weight (lbs.) length int %8.0g Length (in.) turn int %8.0g Turn Circle (ft.) displacement int %8.0g Displacement (cu. in.) gear_ratio float %6.2f Gear Ratio foreign byte %8.0g origin Car type -------------------------------------------------------------------------------------- Sorted by: foreign . ds, has(varlabel Mile*) mpg . findname , varlabeltext(Mile*) mpg . keep `r(varlist)' . d Contains data from C:\Program Files\Stata10\ado\base/a/auto.dta obs: 74 1978 Automobile Data vars: 1 13 Apr 2007 17:45 size: 444 (99.9% of memory free) (_dta has notes) -------------------------------------------------------------------------------------- storage display value variable name type format label variable label -------------------------------------------------------------------------------------- mpg int %8.0g Mileage (mpg) -------------------------------------------------------------------------------------- Sorted by: Note: dataset has changed since last saved之类的值作为区别，可以方便地从地图等中选择数据。您可以随意使用。

如何知道＆＃34;然后＆＃34;阻止＆＃34;当＆＃34;

2 个答案: