Definition of Whitebeam XML Tags
The body of this tag is always empty.
attribute and replace the value of the tag with the value of the expression.
and to use the <rb:script...> tag for more
It is recommended that the bulk of the Whitebeam Script for a Pattern Page
be included at the head of the page and then accessed through <rb:eval...>
tags or through the equivalent attribute (rb:eval). This is by no means required
but experience has shown that intermingling lots of server side and client side
Processing by the Whitebeam presentation engine (given an appropriate
ROM view) would generate the following
generates output via side-effects (The main example being
rb.page.write) The creates
a potential conflict about how to generate the output from this tag. Should
the implementation use the output generated from the side-effect or
from the result of the expression. To resolve this conflict the Whitebeam
Presentation Engine employs the following rules (in order of precedence):
If the result of the expression is not void then the value is converted
to a string and becomes the result of executing the tag.
If the result of the expression is void and there has been output
generated by the script, for example by 'rb.page.write' then this output
is used to replace the <rb:eval...> tag in the generated page.
If neither of the above is true then there is no output and the
<rb:eval...> tag is removed from the output stream. This is useful
in the case where the Pattern Page wishes to invoke some template
functionality but does not wish to generate output.
Note. To force
may be used as follows:
<rb:eval expr="void (rb.template.read())">
When executed this tag generates no output, regardless of whether
the call to rb.template.read returns a value.
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