Hi!<div><br></div><div>please see my answer below.<br><br><div class="gmail_quote">On Sat, Nov 12, 2011 at 12:03 PM, Gennadiy Rozental <span dir="ltr">&lt;<a href="mailto:rogeeff@gmail.com">rogeeff@gmail.com</a>&gt;</span> wrote:<br>

<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Hi,<br>
<br>
Now I am trying to perform transform which mutates:<br>
<br><br>
int<br>
main()<br>
{<br>
    B b1, b2;<br>
    auto z1 = fusion::make_list( b1, b2 ); !!! create a list of copied Bs<br>
<br>
    auto z2 = fusion::as_list( fusion::transform( z1, make_c() ) ); !!! copies Bs again<br>
<br>
    return 0;<br>
}<br></blockquote><div><br></div><div>You need to make a list of references to Bs: </div><div>This is a slighly modified code which compiled in msvc</div><div><br></div><div><div>#include &lt;boost/fusion/container/list/list.hpp&gt;</div>

<div>#include &lt;boost/fusion/container/list/convert.hpp&gt;</div><div>#include &lt;boost/fusion/container/generation/make_list.hpp&gt;</div><div>#include &lt;boost/fusion/algorithm/transformation/transform.hpp&gt;</div>

<div><br></div><div>#include &lt;boost/ref.hpp&gt;</div><div><br></div><div>using namespace boost;</div><div><br></div><div>struct C {};</div><div><br></div><div>struct B {</div><div>   C   make_c() { return C(); }</div>
<div>
};</div><div><br></div><div>struct make_c {</div><div>   template&lt;typename Sig&gt; struct result;</div><div><br></div><div>   template &lt;typename T&gt;</div><div>   struct  result&lt;make_c(T&amp;)&gt;</div><div>   {</div>

<div>       typedef C type;</div><div>   };</div><div>   template &lt;typename T&gt;</div><div>   struct  result&lt;make_c(T)&gt;</div><div>   {</div><div>       typedef C type;</div><div>   };</div><div><br></div><div>   template &lt;typename T&gt;</div>

<div>   C</div><div>   operator()(T&amp; t) const { return t.make_c(); }</div><div>};</div><div><br></div><div>int</div><div>main()</div><div>{</div><div>   B b1, b2;</div><div>   auto z1 = fusion::make_list( ref(b1), ref(b2) );</div>

<div><br></div><div>   auto z2 = fusion::as_list( fusion::transform( z1, make_c() ) );</div><div><br></div><div>   return 0;</div><div>}</div></div></div><br></div><div>Regards,</div><div>Ovanes</div>