2

What is the best method, to change the previously declared function into the new one?

for example, there is already declared:

function smth(){
echo 'aaa';
}

and i want that it displayed not aaa, but bbb

function smth(){
echo 'bbb';
}

but when i insert the new function (inside functions.php), i get error message

(Fatal error: Cannot redeclare **smth()** (previously declared in ... )



UPDATE - I have found a solution:

https://stackoverflow.com/a/8125517/2165415

3

PHP cannot redeclare functions. You will need to use some other approach, like filters or similar.

3

PHP doesn't allow to redeclare functions. If you write the original function, there aare a lot of ways to allow you to write a more flexible functions.

Conditional on passed arguments and filter hook, are first that comes into my mind.

EX. 1:

function smth( $out = 'a' ){
  if ( $out === 'a' ) {
    echo 'aaa';
  } else {
    echo 'bbb';
  }
}

After that, first time call

smth();

and second time:

smth('b');

EX. 2

function smth(){
  echo apply_filters('my_smth_filter', 'aaa');
}

After that, first time call

smth();

and second time:

add_filter('my_smth_filter', function() {
  return 'bbb';
});
smth();

If the original function is not function of yours and it doesn't provide any filter to change output and you absolutely need to change that function behaviour, then look at Patchwork, a PHP library that lets you redefine user-defined functions at runtime. However use Patchwork with caution and only if absolutely necessary, because Patchwork is intended to be used for testing purpose, not on production.

1

I would suggest to use OOP approach, like:

class SomeClass
{
  public function aa()
  {
     echo 'aa';
  }
}

class SomeOtherClass extends SomeClass
{
   public function aa()
   {
      return 'bb';
   }
}

$a = new SomeClass();
$a->aa(); // outputs aa
$b = new SomeOtherClass();
$b->aa(); // outputs bb

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