Question

I was wondering if PHP can do this as there seems to be no good solution to it yet:

p($i)

and it will print

$i is 5

and

p(1 + 2)

will print

1 + 2 is 3

and

p($i * 2)  =>  $i * 2 is 10  
p(3 * factorial(3))  =>  3 * factorial(3) is 18

C and Ruby both can do it… in C, it can be done by stringification, and in Ruby, there is a solution using p{'i'} or p{'1 + 2'} (by passing the block with the binding over, to do an eval)… I wonder in PHP, is it possible too?

Answer 1

I think it could be done by taking a backtrace then loading and tokenizing the file that calls p(). I wouldn’t call it a “good” solution though.

Of course you could stringify it yourself…

p('$i');

function p($str) 
{
    echo $str, " = ", eval("return ($str);");
}