(PECL spl_types >= 0.1.0)
The SplString class is used to enforce strong typing of the string type.
SplType::__construct ([ mixed $initial_value [, bool $strict ]] )}
SplString::__defaultExample #1 SplString usage example
<?php
$string = new SplString("Testing");
try {
    $string = array();
} catch (UnexpectedValueException $uve) {
    echo $uve->getMessage() . PHP_EOL;
}
var_dump($string);
echo $string; // Outputs "Testing"
?> The above example will output:
Value not a string
object(SplString)#1 (1) {
  ["__default"]=>
  string(7) "Testing"
}
Testing
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    https://www.php.net/manual/en/class.splstring.php