Functions Delphi

Title: Str: a function more useful than a procedure.
Question: I desired to have a str function instead of a Str procedure so.. I built it.
By overloading the functions, Delphi is capable of converting anything to a string.
Besides, you can extend it to any variable type.
Answer:
Here is the code:
interface
function str_(const x : double) : string; overload;
function str_(const x : longint) : string; overload;
function str_(const x : longword) : string; overload;
function str_(const x : boolean) : string; overload;
implementation
function str_(const x: double ) : string; overload;
var aux : string;
begin
str(x:8:2,aux);
str_:=aux;
end;
function str_(const x: longint ) : string; overload;
var aux : string;
begin
str(x:8,aux);
str_:=aux;
end;
function str_(const x: longword) : string; overload;
var aux : string;
begin
str(x:8,aux);
str_:=aux;
end;
function str_(const x: boolean ) : string; overload;
begin
if x then str_:='true' else str_:='false';
end;