Get calling scope in a PHP function?

Question

Can I access the scope of the calling environment from within a called function?

For example, I would like to access __LINE__ in a logging function but it needs to be the __LINE__ from the calling environment. I would also like to have some way of calling get_defined_vars() to get the callers variables.

In both examples it saves having to have an extra argument.

Is this possible?

Answer 1

There's no way to get the callers' variables, but you can get their arguments. This is easily done with debug_backtrace():

<?php

class DebugTest
{
    public static function testFunc($arg1, $arg2) {
        return self::getTrace();
    }

    private static function getTrace() {
        $trace = debug_backtrace();
        return sprintf(
            "This trace function was called by %s (%s:%d) with %d %s: %s\n",
            $trace[1]["function"],
            $trace[1]["file"],
            $trace[1]["line"],
            count($trace[1]["args"]),
            count($trace[1]["args"]) === 1 ? "argument" : "arguments",
            implode(", ", $trace[1]["args"])
        );
    }
}

echo DebugTest::testFunc("foo", "bar");

Running this program, we get this output:

This trace function was called by testFunc (/Users/mike/debug.php:23) with 2 arguments: foo, bar

debug_backtrace() returns an array; element 0 is the function in which the function itself was called, so we use element 1 in the example. You can use a loop to travel all the way back up the trace.