org.aspectj/docs/adk15ProgGuideDB/miscellaneous.xml

<chapter id="miscellaneous" xreflabel="Miscellaneous Changes">

  <title>Other Changes in AspectJ 5</title>

  <sect1 id="pointcuts-change">
      <title>Pointcuts</title>

          <para>
           AspectJ 5 is more liberal than AspectJ 1.2.1 in accepting pointcut expressions
           that bind context variables in more than one location. For example, AspectJ
           1.2.1 does not allow:
           </para>

       	<programlisting><![CDATA[
pointcut foo(Foo foo) : (execution(* *(..)) && this(foo) ) ||
                        (set(* *) && target(foo));
]]></programlisting>

		 <para>
		     whereas this expression is permitted in AspectJ 5. Each context variable must
		     be bound exactly once in each branch of a disjunction, and the disjunctive branches
		     must be mutually exclusive. In the above example for instance, no join point
		     can be both an execution join point and a set join point so the two branches
		     are mutually exclusive.
		  </para>

  </sect1>

  <sect1 id="declare-soft-change">
      <title>Declare Soft</title>
      <para>
          The semantics of the <literal>declare soft</literal> statement have been
          refined in AspectJ 5 to only soften exceptions that are not already runtime
          exceptions. If the exception type specified in a declare soft statement is <literal>RuntimeException</literal>
          or a subtype of <literal>RuntimeException</literal> then a new XLint warning will be issued:</para>

       	<programlisting><![CDATA[
declare soft : SomeRuntimeException : execution(* *(..));

>> "SomeRuntimeException will not be softened as it is already a RuntimeException" [XLint:runtimeExceptionNotSoftened]
]]></programlisting>

	   <para>
	       This XLint message can be controlled by setting the <literal>runtimeExceptionNotSoftened</literal> XLint parameter.
 	   </para>

	   <para>
	      If the exception type specified in a declare soft statement is a super type of <literal>RuntimeException</literal>
	      (such as <literal>Exception</literal> for example) then any <emphasis>checked</emphasis> exception thrown at a matched join point,
	      where the exception is an instance of the softened exception, will be softened to an
	      <literal>org.aspectj.lang.SoftException</literal>.
      </para>

       	<programlisting><![CDATA[
public aspect SoftenExample {
  declare soft : Exception : execution(* Foo.*(..));
}

class Foo {
  public static void main(String[] args) {
    Foo foo = new Foo();
    foo.foo();
    foo.bar();
  }

  void foo() throws Exception {
    throw new Exception();        // this will be converted to a SoftException
  }

  void bar() throws Exception {
    throw new RuntimeException();  // this will remain a RuntimeException
  }
}
]]></programlisting>


  </sect1>


</chapter>