Hi !<br><br>the question is in the subject, but I can elaborate a bit. I have the set of all views supported by my application, defined as :<br><br>  typedef mpl::vector9&lt;<br>      gray8_view_t<br>    , rgb8_view_t, bgr8_view_t, rgba8_view_t, bgra8_view_t<br>
    , rgb32f_view_t, bgr32f_view_t, rgba32f_view_t, bgra32f_view_t<br>    &gt;<br>    gil_all_views_t;<br><br>  typedef any_image_view&lt;gil_all_views_t&gt; any_view;<br><br>Then I have a function, reading a file and returning an any_image_view, of a different type :<br>
<br>typedef boost::mpl::vector3&lt;boost::gil::gray8_view_t, boost::gil::bgr8_view_t, boost::gil::bgra8_view_t&gt; tga_views_t;<br>typedef boost::gil::any_image_view&lt;tga_views_t&gt; any_tga_view;<br><br>The &#39; tga_views_t&#39; is a subset of &#39;gil_all_views_t&#39;.<br>
<br>It seems that I cannot construct an &#39;any_view&#39; instance, from an &#39;any_tga_view&#39; ; I receive a bad_cast exception.<br><br>Is there an existing function or construct I could use for this ?<br><br>If I&#39;m not mistaken, boost::variant (not the gil one) allow such constructs : it extracts the type of the value contained in the &#39;foreign&#39; variant, and assigns this value to the new variant.<br>
<br>Anyone could tell me what is the rationale behind having a special variant for boost::gil ? performance ? Wouldn&#39;t it be easier to replace it by boost::variant ?<br><br>Thanks is advance,<br>cheers,<br><br>Nicolas.<br>