Return function results based on condition - PHP

Question

I have the following code

public function create(){
  return self::checkQuantity();
  return self::checkSameLocation();
  return self::someAnotherFunction();
  return self::someMoreFunction();
  ..
  ..
  ..

}

public function checkQuantity(){
  if(someCondition){
     return [foo,bar];
  }
}


public function checkSameLocation(){
  if(someCondition){
     return [foo,bar];
  }
}

I would like to return function inside create() only if it function inside it returns something else continue executing the create() function.

Based on the example:

create() gets called
if checkQuantity returns nothing then continue with checkSameLocation() without returning checkQuantity() function

NOTE: There could be multiple function calls inside create() sometimes, I would like to avoid using if statement checks.

Without doing if checks, because if there are 10 functions calls that would make it messy. — Rehan, Nov 19 '19 at 16:21
Without `if` checks you can't check __if__ nothing returned from first function — u_mulder, Nov 19 '19 at 16:22
Im not sure what it is your functions return, are these functions wrapped in a class? You cant check if nothing returned from a function because it will always return null. — Thomas Gregory, Nov 19 '19 at 16:25
In terms of OOD, I guess a suitable solution would be [chain of responsibility](https://refactoring.guru/design-patterns/chain-of-responsibility/php/example#example-1) — Andrii Filenko, Nov 19 '19 at 16:35

Weltschmerz · Accepted Answer · 2019-11-19T16:31:23.350

3

public function create(){
    return self::checkQuantity()
           ?? self::checkSameLocation()
           ?? self::someAnotherFunction(); //and so on
}

See Null coalescing operator

edited Nov 19 '19 at 16:31

answered Nov 19 '19 at 16:25

Weltschmerz

2,166
1
15
18

This is much better than `if.. else`, much cleaner. I was looking for this. Thanks. – Rehan Nov 19 '19 at 16:30

score 2 · Answer 2 · answered Nov 19 '19 at 16:26

public function create(){
  $data = function1();
  if ($data) { 
    return $data;
  }

  $data = function2();
  if ($data) { 
    return $data;
  }

  $data = function3();
  if ($data) { 
    return $data;
  }

  // ...

  return function42();
}

This can lead to another solution like:

public function create(){
  $functions = ['func1', 'func2', 'func3',]; // etc
  foreach ($functions as $func) {
    $data = $func();
    if ($data) { 
      return $data;
    }
  }
}

score 2 · Answer 3 · answered Nov 19 '19 at 16:31

2

Something like this:

(in this case, I've moved all your check code into polymorphic classes; the same could be achieved with methods in the current class per your question, but I think it's neater this way)

$checks = [new checkClass1, new checkClass2, new checkClass3, ...];

foreach ($checks as $check) {
    $result = $check->runCheck();
    if ($result) {
        return $result;
    }
}

answered Nov 19 '19 at 16:31

Spudley

166,037
39
233
307

Thanks for the answer. But coalesce operator is much cleaner approaches for my use case. – Rehan Nov 19 '19 at 16:33

score 0 · Answer 4 · answered Nov 19 '19 at 16:23

0

You need an if and a temporary variable.

public function create(){
  $a = self::checkQuantity();
  if(empty($a)) { 
    return self::checkSameLocation();
  } else {
    return $a;
  }
}

public function checkQuantity(){
  if(someCondition){
     return [foo,bar];
  }
}


public function checkSameLocation(){
  if(someCondition){
     return [foo,bar];
  }
}

answered Nov 19 '19 at 16:23

Adder

5,708
1
28
56

What if, there is more than 2 functions? Please check updated question. – Rehan Nov 19 '19 at 16:24

score 0 · Answer 5 · answered Nov 19 '19 at 16:32

This looks like the perfect use case for the null coalescing operator

public function create(){
  return self::checkQuantity() ?? self::checkSameLocation() ?? self::someAnotherFunction() ?? return self::someMoreFunction()...
}

You can chain as many function calls as you want. That line will return the first value that's not null. Since returning nothing from a function effectively equals returning a null value, it'll work as you want.

Return function results based on condition - PHP

5 Answers5