'&'和'!'的含义是什么？在属性名称之前？

Question

我正在阅读别人写的WIX脚本.有些代码让我很困惑.

<Custom Action='UnLoadSchedulerPerfCounters' After='InstallInitialize'>
    <![CDATA[(Installed) AND (!Scheduler = 3)]]>
</Custom>
<Custom Action='RollbackSchedulerPerfCounters' After='WriteRegistryValues'>
        <![CDATA[(&Scheduler = 3)]]>
</Custom>

那么,!Scheduler和之间的区别是&Scheduler什么？当属性前缀为&或时,是否有任何特殊含义!？

Answer 1

来自http://www.tramontana.co.hu/wix/lesson5.php#5.3:

在名称前面添加一些特殊字符将赋予它们额外的含义:

%     environment variable (name is case insensitive)
$     action state of component
?     installed state of component
&     action state of feature
!     installed state of feature

最后四个可以返回以下整数值:

-1   no action to be taken
1    advertised (only for components)
2    not present
3    on the local computer
4    run from the source

Answer 2

这些是Windows Installer条件语法的运算符.有关完整列表,请参阅此MSI SDK文档:http: //msdn.microsoft.com/en-us/library/aa368012.aspx.