PHP Start loop in one function and end it in another?

Question

I'm building my personal Database connection model and one thing that I needed to do is allow the user to start a loop using a function and end the loop in another function. This is the code:

Code for running the functions

PSMQuery::loopQueryStart("DATA");
  // Stuff that can be executed in the loop
PSMQuery::loopQueryStop();

Code in the class:

public function loopQueryStart($query) {
  while (CONDITION):
}

public function loopQueryEnd() {
  endwhile;
}

And I was wondering if this method should work and if there would be another way, just to simplify the look of the code for someone using my model.

@Federico a loop being started with a function, the in the middle the user can use their input then another function which will close the loop. - kind of like the CodeIgniter method for Auth — Jack Hales
– Jack Hales, Commented Apr 9, 2016 at 0:06
This makes no sense to me. Can't you just pass a function/reference to, eg PSMQuery::loop("Data", function($var) { /* sth */})? — kero
– kero, Commented Apr 9, 2016 at 0:10
Why wouldn't you have your loopQueryEnd function make the CONDITION false, thus ending the while loop? — BLE
– BLE, Commented Apr 9, 2016 at 0:37

kero · Accepted Answer · 2016-04-09 00:56:47Z

2

As I stated in my comment, I do not think this is a good idea. Yes, WordPress' loop comes to mind, but it just feels dirty to me.

What I would suggest are Callbacks / Callables. This way you do not need to start and end the loop in different functions and can simply pass a function to call inside the loop. I have prepared this working example. Your code could look like this

PSMQuery::loopQuery("Data", function($data) {
    // return something
});

//***

public static function loopQuery($data, callable $callback) {
   while (loop) {
       // do something with $callback
   }
}

If you want to manipulate in a more complex way, references might help you find a solution

answered Apr 9, 2016 at 0:56

kero

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6 Comments

Jack Hales Over a year ago

After being confused for a while I finally got it, thanks for the answer :)

Paweł Witek Over a year ago

@kero Still I would opt and drag about @JackHales soslution. Take for example wordpress. It would be much cleaner to have php structure like start_loop(); echo $title; end_loop().

kero Over a year ago

@PawełWitek Even with WP you'd usually do while (have_posts()) { the_post(); /* your code */ }. In the end it is more a question of style of code I'd say - and I stick with my original message, that I prefer it with a callback, this way it is all combined and not one method call here, another one somewhere else.

Paweł Witek Over a year ago

@kero yes, you're right, I do that by myself, I've created snippet to print this out for ease of use and its easy however my thinking is purly esthetics :) and I wonder if this open / close loop functions are even possible? have a great day! ^^

kero Over a year ago

@PawełWitek In templating you usually do it like this, that your calls get transpiled to while(): and endwhile;. With this, you can restructure it around multiple files/calls/whatever, but for me it always feels just too messy

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