I have a log() method and want to log the name of the script that called it. How is that possible in PHP?
Depending on the calling environment, you should have a look at debug_backtrace, and $_SERVER['PHP_SELF']
debug_backtrace() will give you a stack trace of the includes and function calls so far, and $_SERVER['PHP_SELF'] will tell you the currently executing script, which is easier and might work just as well for what you want. $_SERVER['PHP_SELF'] will pretty much always be the script that was called from the browser, for example, if you had blah.com/admin.php and blah.com/articles.php that both called /pages.php to get a list of the pages saved in a blog or something, and something went wrong -- the log would tell you whether admin.php or articles.php was calling the script. But if pages.php included functions.php which included libs.php and libs.php failed, and you wanted to know that functions.php included it, this wouldn't work -- the log would still show the script that started the including (admin.php or articles.php). In this case you would use debug_backtrace().