We have updated C# XOM (csharpxom) to support C# 4.0 (in fact there are very few changes).

From the grammar perspective this includes:

• Dynamic types;
• Named and optional arguments;
• Covariance and contravariance of generic parameters for interfaces and delegates.

Dynamic type, C#:

dynamic dyn = 1;

C# XOM:

<var name="dyn">
  <type name="dynamic"/>
  <initialize>
    <int value="1"/>
  </initialize>
</var>

Named and Optional Arguments, C#:

int Increment(int value, int increment = 1)
{
  return value + increment;
}

void Test()
{
  // Regular call.
  Increment(7, 1);

  // Call with named parameter.
  Increment(value: 7, increment: 1);
 
  // Call with default.
  Increment(7);
}

C# XOM:

<method name="Increment">
  <returns>
    <type name="int"/>
  </returns>
  <parameters>
    <parameter name="value">
      <type name="int"/>
    </parameter>
    <parameter name="increment">
      <type name="int"/>
      <initialize>
        <int value="1"/>
      </initialize>
    </parameter>
  </parameters>
  <block>
    <return>
      <add>
        <var-ref name="value"/>
        <var-ref name="increment"/>
      </add>
    </return>
  </block>
</method>

<method name="Test">
  <block>
    <expression>
      <comment>Regular call.</comment>
      <invoke>
        <method-ref name="Increment"/>
        <arguments>
          <int value="7"/>
          <int value="1"/>
        </arguments>
      </invoke>
    </expression>

    <expression>
      <comment>Call with named parameter.</comment>
      <invoke>
        <method-ref name="Increment"/>
        <arguments>
          <argument name="value">
            <int value="7"/>
          </argument>
          <argument name="increment">
            <int value="1"/>
          </argument>
        </arguments>
      </invoke>
    </expression>

    <expression>
      <comment>Call with default.</comment>
      <invoke>
        <method-ref name="Increment"/>
        <arguments>
          <int value="7"/>
        </arguments>
      </invoke>
    </expression>
  </block>
</method>

Covariance and contravariance, C#:

public interface Variance<in T, out P, Q>
{
  P X(T t);
}

C# XOM:

<interface access="public" name="Variance">
  <type-parameters>
    <type-parameter name="T" variance="in"/>
    <type-parameter name="P" variance="out"/>
    <type-parameter name="Q"/>
  </type-parameters>
  <method name="X">
    <returns>
      <type name="P"/>
    </returns>
    <parameters>
      <parameter name="t">
        <type name="T"/>
      </parameter>
    </parameters>
  </method>
</interface>

Other cosmetic fixes were also introduced into Java XOM (jxom), COBOL XOM (cobolxom), and into sql XOM (sqlxom).

The new version is found at languages-xom.zip.

See also: What's New in Visual C# 2010