Evaluating code

Hi, I have code stored on a server which I retrieve via fsockopen() and put it into a variable (It's like if it were on a database). Now, I want to eval that code, but eval() won't work because it has HTML and PHP mixed, with <?php ?> and everything. I know I can eval this code saving it to a file and then including it, but I want to know if there's a better way. As I'm going to do this all the time, I prefer not to create temporary files (so I don't slow down everything). Any ideas? Thanks in advance, Ernesto