<include> w/ parameterized value

[johncorro]

Does anyone know how to declare an attribute within a library class and then reference it's value from an <include> tag as such:

<library>
<class name="baseview" extends="view">
<attribute name="headerview" value="null"/>
<attribute name="secondaryview" value="null"/>
<attribute name="primaryview" value="null"/>

<view name="LayoutView">
...
<include href="${headerview}"/>
...
<include href="${secondaryview}"/>
...
<include href="${primaryview}"/>
...
</view>
</class>
</library>

When I try executing this it seems as if Laszlo isn't trying to resolve the value of '${...}', bur rather is using the value as a literal.