Description:
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My feature request is to have support for string functions inside a php SplString so it's normalized under this object and that it can be made easy to manipulate strings.

A few examples in PHP

$b = new SplString("A String");
$a = $b->replace("A", "The");
// $a == "The String" , $b == "A String"

$a->replace("The", "Thy");
print $a // $a == "Thy String");

print $a->substr(0, 3); // "Thy "

print $a->indexOf("T"); // 0