Question

My question is similar to this: Is it possible to run code after each line in Ruby?
However I want to do it in PHP.

Is it possible and if so, how?

Answer 1

You can register a tick handler:

Ticks

A tick is an event that occurs for every N low-level tickable statements executed by the parser within the declare block. The value for N is specified using ticks=N within the declare blocks’s directive section.

Not all statements are tickable. Typically, condition expressions and argument expressions are not tickable.

As you can see, it’s not exactly as "each line of code" unless you only write one tickable statement each line. But it’s the closest you can get.

Example:

declare(ticks=1);
register_tick_function(function() {
    echo "tick_handler() called\n";
});

echo 'Line 1', PHP_EOL;
echo 'Line 2', PHP_EOL;
echo strtoupper('Line 3'), PHP_EOL;

will output (demo):

tick_handler() called
Line 1
tick_handler() called
Line 2
tick_handler() called
LINE 3
tick_handler() called