Wix使用整理(四)

安装过程中，有时候需要根据用户的设置来进行不同的安装，其中一个方面就是根据用户选择安装的Feature或者Component，来判断下一步的操作。
??? Wix中提供了相关的判断方法和内置的状态值。
??? Prepending some special characters to the names will give them extra meaning:
??? %??environment variable (name is case insensitive)
?? ?$? ?action state of component
??? ?? ?installed state of component
??? &? ?action state of feature
??? !? ?installed state of feature

??? The last four can return the following integer values:
?? -1? ?no action to be taken
?? 1? ?advertised (only for components)
?? 2? ?not present
?? 3? ?on the local computer
?? 4? ?run from the source

A few examples to make things clearer:

(&FeatureName = 3) AND NOT (!FeatureName = 3)

Run action only if the product will be installed locally. Do not run action on a reinstallation.

The term &FeatureName = 3 means the action is to install the feature locally.

The term NOT (!FeatureName = 3) means the feature is not installed locally.

?

?(&FeatureName = 2) AND (!FeatureName = 3)

Run action only if the feature will be uninstalled.

This condition only checks for a transition of the feature from an installed state of local to the absent state.

?

(?ComponentName = 3) AND ($ComponentName = 2 OR $ComponentName = 4)

Run action only if the component was installed locally, but is transitioning out of state.

The term ?ComponentName = 3 means the component is installed locally.

The term $ComponentName = 2 means that the action state on the component is absent.

The term $ComponentName = 4 means that the action state on the component is run from source. Note that an action state of advertise is not valid for a component.

?

?ComponentName = $ComponentName

Run action only on the reinstallation of a component.