Using c:url in c:set

Question

I need to use some link as argument to <spring:message /> and use <c:set/> for that. To have link relative to contextPath i use <c:url>. Why using <c:url/> in <c:set/> inside like below doesn't work ?

<c:set value='<c:url value="/x"/>' var='doc1'/>
<spring:message code="doc.link" arguments="${doc1}"/> <%-- ${doc1} is empty --%>

Simlar using <a href/> works good:

<c:set value='<a href="/fullurl/x">here</a>' var='doc1'/>
<spring:message code="doc.link" arguments="${doc1}"/>

messages.properties:

doc.link = Doc is {0}

EDIT I need to work exactly something like that:

<c:set value='<a href="<c:url value="/x"/>">here</a>' var='doc1'/>

Answer 1

Put it in the tag body:

<c:set var="doc1"><a href="<c:url value="/x" />">here</a></c:set>
<spring:message code="doc.link" arguments="${doc1}"/>

Or if you want XML well-formness:

<c:url var="url" value="/x" />
<c:set var="doc1"><a href="${url}">here</a></c:set>
<spring:message code="doc.link" arguments="${doc1}"/>

Answer 2

<c:url> has an option to set the result to a variable, rather than outputting it. Just set the var attribute.

<c:url value="..." var="doc1" />