mple:

</p>
<pre class="programlisting">
int i = 1; int j = 2; 
(_1 + _2)(i, j); // ok
(_1 + _2)(1, 2); // error (!)
</pre>
<p>

	This restriction is not as bad as it may look. 
	Since the lambda functors are most often called inside STL-algorithms, 
	the arguments originate from dereferencing iterators and the dereferencing operators seldom return rvalues.
	And for the cases where they do, there are workarounds discussed in 
<a class="xref" href="le_in_details.html#lambda.rvalues_as_actual_arguments" title