Länge eines Strings

Guten Tag

In eine anderen Forum bin ich auf folgenden Eintrag gestossen:

Make 'toto' a variable of type LINE, from package STD.TEXTIO.
Then you can copy any string into it using the WRITE procedure:

variable toto: LINE; -- initialised to empty!
...
if A=0 then
WRITE(toto, t1);
else
WRITE(toto, t2);
end if;

Don't forget that the WRITE procedure adds things to the end
of the string stored in 'toto', so that it grows ever longer.
To reset it back to "empty", simply:

DEALLOCATE(toto);

Which leads us to an attractive procedure that has the effect
of copying any string into a LINE variable, having first
cleared that variable:

procedure put(L: inout LINE; S: in STRING) is
begin
DEALLOCATE(L);
WRITE(L, S);
end;

Now, of course, you have the problem of how to make use of
the string contents of the line variable. Given a variable
L of type LINE, you can...
* get hold of the whole string contents:
report "Message is " & L.ALL;
* take a slice of it, just like a string:
variable c: CHARACTER;
...
c := L(1);
* find its length:
if L'LENGTH > 50 then ...

Allerdings funktioniert bei mir das Attribut 'LENGTH sowie die Procedur 
DEALLOCATE nicht! Die STD-Library habe ich eingebunden und auch das File 
STD.TEXTIO.ALL.
Hat jemand eine andere Lösung, die Anzahl Zeichen in einer Line zu 
ermitteln, sowie die Line zu löschen?

Gruss
Thomas