PHP 4 adds a new mechanism to variable substitution in
    strings. You can now finally access object member variables and
    elements from multidimensional arrays within strings.
   
    To do so you have to enclose your variables with curly braces with
    the dollar sign immediately following the opening brace:
    {$...}
   
    To embed the value of an object member variable into a string you
    simply write "text {$obj->member} text" while
    in PHP 3 you had to use something like "text
    ".$obj->member." text".
   
    This should lead to more readable code, while it may break
    existing scripts written for PHP 3. But you can easily check for
    this kind of problem by checking for the character combination
    {$ in your code and by replacing it with
    \{$ with your favorite search-and-replace
    tool.