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<conditions>
   <condition type="variable" id="standardinstallation">
      <name>setup.type</name>
      <value>standard</value>
   </condition>
   <condition type="variable" id="expertinstallation">
      <name>setup.type</name>
      <value>expert</value>
   </condition>
   <condition type="java" id="installonwindows">
 <java>
   <class>com.izforge.izpack.util.OsVersion</class>
   <field>IS_WINDOWS</field>
 </java>
 <returnvalue type="boolean">true</returnvalue>
 </condition>
 <condition type="and" id="standardinstallation.onwindows">
   <condition type="ref" refid="standardinstallation"/>
   <condition type="ref" refid="installonwindows" />
 </condition>
</conditions>

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Expression languages

Simple expression language

From IzPack 3.11 on normally, you don't have to define the compound conditions because you can use a simple expression language. The language has supports the following operators:

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Thus, !conditionA+conditionB+!conditionC DOES NOT equal (!conditionA) && conditionB && (!conditionC), but equals !(conditionA && (conditionB && !(conditionC))).

So you should definecomplex define complex conditions using the xml structure or use the Complex expression language.

Complex expression language

With IZPACK-577 fixed and released, you can also use a more Complex expression language that evaluates using the boolean precedence rules.

!conditionA+conditionB+!conditionC equals (!conditionA) && conditionB && (!conditionC).

XOR and parentheses () may be added in the future.

More types of conditions can be defined by inheriting com.izforge.izpack.Condition class.

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