Asked  7 Months ago    Answers:  5   Viewed   41 times

If I use array_walk inside a class function to call another function of the same class

class user
{
   public function getUserFields($userIdsArray,$fieldsArray)
   {

     if((isNonEmptyArray($userIdsArray)) && (isNonEmptyArray($fieldsArray)))
     {
         array_walk($fieldsArray, 'test_print');
     }
   }


  private function test_print($item, $key)
  {
         //replace the $item if it matches something
  }

}

It gives me the following error -

Warning: array_walk() [function.array-walk]: Unable to call test_print() - function does not exist in ...

So, how do I specify $this->test_print() while using array_walk()?

 Answers

68

If you want to specify a class method as a callback, you need to specify the object it belongs to:

array_walk($fieldsArray, array($this, 'test_print'));

From the manual:

A method of an instantiated object is passed as an array containing an object at index 0 and the method name at index 1.

Wednesday, March 31, 2021
 
Fanda
answered 7 Months ago
92

not pretty but heres how I would do it with a nested foreach;

$aStartingArray = array();
$aStartingArray[] = array('source'=>'ABC', 'target' => 'DEF', 'total_volume' => 10); 
$aStartingArray[] = array('source'=>'ABC', 'target' => 'GHI', 'total_volume' => 5); 
$aStartingArray[] = array('source'=>'ABC', 'target' => 'DEF', 'total_volume' => 5); 


$aSortedArray = array();

foreach ($aStartingArray as $aArray) {

    $bSet = false;

    foreach ($aSortedArray as $iPos => $aTempSortedArray) {

        if(
            $aTempSortedArray['source'] == $aArray['source'] && 
            $aTempSortedArray['target'] == $aArray['target']){

            $aSortedArray[$iPos]['total_volume'] += $aArray['total_volume'];

            $bSet = true;
        }

    }

    if(!$bSet) {

        $aSortedArray[] = array(
            'source' => $aArray['source'], 
            'target' => $aArray['target'], 
            'total_volume' => $aArray['total_volume']
            );
    }
}


var_dump($aSortedArray);
Wednesday, March 31, 2021
 
supermitch
answered 7 Months ago
14

As you can read on php callback page, you shall use:

# produces an error
array_walk($array, array($msqli, 'real_escape_string'));
array_map($array, array($msqli, 'real_escape_string'));
Saturday, May 29, 2021
 
drowneath
answered 5 Months ago
64

No, you cannot, because the class definition has not yet completed running so the class name doesn't exist yet in the current namespace.

You can use the function object directly:

class C:    
    @staticmethod
    def default_concrete_strategy():
        print("default")

    @staticmethod
    def other_concrete_strategy():
        print("other")

    def __init__(self, strategy=default_concrete_strategy.__func__):
        self.strategy = strategy

C doesn't exist yet when the methods are being defined, so you refer to default_concrete_strategy by the local name. .__func__ unwraps the staticmethod descriptor to access the underlying original function (a staticmethod descriptor is not itself callable).

Another approach would be to use a sentinel default; None would work fine here since all normal values for strategy are static functions:

class C:    
    @staticmethod
    def default_concrete_strategy():
        print("default")

    @staticmethod
    def other_concrete_strategy():
        print("other")

    def __init__(self, strategy=None):
        if strategy is None:
            strategy = self.default_concrete_strategy
        self.strategy = strategy

Since this retrieves default_concrete_strategy from self the descriptor protocol is invoked and the (unbound) function is returned by the staticmethod descriptor itself, well after the class definition has completed.

Monday, August 16, 2021
 
e_i_pi
answered 2 Months ago
61

You have to import it and call it like this:

import printer as pr

pr.Printer().printMessage()
Sunday, August 22, 2021
 
Howard
answered 2 Months ago
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