Coalesce function for PHP?

There is a new operator in php 5.3 which does this: ?:

// A
echo 'A' ?: 'B';

// B
echo '' ?: 'B';

// B
echo false ?: 'B';

// B
echo null ?: 'B';

Source: http://www.php.net/ChangeLog-5.php#5.3.0

First hit for "php coalesce" on google.

function coalesce() {
  $args = func_get_args();
  foreach ($args as $arg) {
    if (!empty($arg)) {
      return $arg;
    }
  }
  return NULL;
}

http://drupial.com/content/php-coalesce

I really like the ?: operator. Unfortunately, it is not yet implemented on my production environment. So I use the equivalent of this:

function coalesce() {
  return array_shift(array_filter(func_get_args()));
}

Make sure you identify exactly how you want this function to work with certain types. PHP has a wide variety of type-checking or similar functions, so make sure you know how they work. This is an example comparison of is_null() and empty()

$testData = array(
  'FALSE'   => FALSE
  ,'0'      => 0
  ,'"0"'    => "0"  
  ,'NULL'   => NULL
  ,'array()'=> array()
  ,'new stdClass()' => new stdClass()
  ,'$undef' => $undef
);

foreach ( $testData as $key => $var )
{
  echo "$key " . (( empty( $var ) ) ? 'is' : 'is not') . " empty<br>";
  echo "$key " . (( is_null( $var ) ) ? 'is' : 'is not')  . " null<br>";
  echo '<hr>';
}

As you can see, empty() returns true for all of these, but is_null() only does so for 2 of them.

I'm currently using this, but I wonder if it couldn't be improved with some of the new features in PHP 5.

function coalesce() {
  $args = func_get_args();
  foreach ($args as $arg) {
    if (!empty($arg)) {
    return $arg;
    }
  }
  return $args[0];
}

A function to return the first non-NULL value:

  function coalesce(&...$args) { // ... as of PHP 5.6
    foreach ($args as $arg) {
      if (isset($arg)) return $arg;
    }
  }

Equivalent to $var1 ?? $var2 ?? null in PHP 7+.

A function to return the first non-empty value:

  function coalesce(&...$args) {
    foreach ($args as $arg) {
      if (!empty($arg)) return $arg;
    }
  }

Equivalent to (isset($var1) ? $var1 : null) ?: (isset($var2) ? $var2 : null) ?: null in PHP 5.3+.

The above will consider a numerical string of "0.00" as non-empty. Typically coming from a HTTP GET, HTTP POST, browser cookie or the MySQL driver passing a float or decimal as numerical string.

A function to return the first variable that is not undefined, null, (bool)false, (int)0, (float)0.00, (string)"", (string)"0", (string)"0.00", (array)[]:

  function coalesce(&...$args) {
    foreach ($args as $arg) {
      if (!empty($arg) && (!is_numeric($arg) || (float)$arg!= 0)) return $arg;
    }
  }

To be used like:

$myvar = coalesce($var1, $var2, $var3, ...);