Can I include a PHP file in an SHTML file and store the result in a SHTML variable?

Question

I want to include a PHP file in an SHTML file and store the result in a SHTML variable and include different things depending on the result.

Example:
Assume the PHP

Answer 1

The answer seems to be NO.

NOTE: It should probably be implemented solely using PHP and a server directive to treat .shtml files as PHP.