Conditional sub-templates?

Hi,
Is it possible to include a sub-template conditionally? Something like this:

if ($var == 1) include("subtemplate1");
else if ($var == 2) include("subtemplate2");

I looked around with conditional statements and subtemplates, but I haven't found a way...

Thanks.

Something like this can work:

But if the sub-template selection is very complicated, then you can calculate it in the PHP side, and then use a variable:

Thanks for the help!