I do not know if I can get the same result with the current PHP features without taking many turns. So I thought of a feature that I'm initially calling "interruptions" (similar to those that occur on a CPU).
Nowadays we have the Exceptions, which stop the execution of a function and initiate a process of "catch" and treatment of the same. So I thought of something similar, but did not break the execution flow, allowing reactions to depend on what was happening inside a function. It would basically work according to the following flow (the square brackets number is the execution order): function sum(int $a, int $b): int { [2] interrupts with new SumInterruption($a, $b); [5] return $a + $b; } interruptable { [6] $sum = [1] sum(1, 2); [7] printf($sum); } [3] catch (SumInterruption $interruption) { [4] printf('Calculating: %d + %d = ', $interruption->a, $interruption->b); } Using current PHP features I can do like that: https://pastebin.com/Bci6BBfi Note that all code will be executed, and the interpection will only redirect temporarily the execution flow to the "catch" block, then will back to "sum()" block to return the sum. Like Exceptions, an Interruption will traverse the code execution tree until find a interruption catch block, but if it doesn't exists, just not will happen (or maybe throw InterruptionNotHandledException or something like it). In one of my real example cases, I have a code that could be manipulated by another method. Currently I need argument the self instance to this method, so it could run another method from the caller method to make some adjustments, which is a bit confuses. I hope you understand my point, and I am open to discuss that. Thanks! -- David Rodrigues