Is it possible to use "english hijrah" on-the-fly without ALTER SESSION?

Question

SQL> alter session set nls_calendar='english hijrah';
Session altered.
SQL> select '29-02-1435', TO_DATE('29-02-1435', 'DD-MM-RRRR') from dual;
'29-02-1435' TO_DATE('29-02-1435','DD-MM-RRRR')
29-02-1435 29 Safar 1435
Hi, the above shows that an input date of '29-02-1435' can be validated as a correct Hijrah date.
However, is it possible to do such a TO_DATE(), or TO_CHAR() conversion without the overhead of an 'ALTER SESSION' at the start ?
From within a Gregorian session I tried a few things like below, but they didn't work and give ORA-01756: quoted string not properly terminated
select TO_CHAR('29-02-1435', 'nls_calendar="English Hijrah"', 'nls_date_format="DD-MM-RRRR")
from dual;
All we're needing to do is validate the date as valid Hijrah - no further processing is done.
Many thanks for any help. Mark

Answer 1

Sorry - I had been confusing single and double quotes.
The following shows that it's a valid Arabic date
SQL> select '29-02-1435', TO_DATE('29-02-1435', 'DD-MM-RRRR', 'nls_calendar=''English Hijrah''')
2 from dual;
'29-02-1435' TO_DATE('29-02-
29-02-1435 02-JAN-14
and for example if you put a crazy month, it complains
SQL> select '29-02-1435', TO_DATE('29-92-1435', 'DD-MM-RRRR', 'nls_calendar=''English Hijrah''')
2 from dual;
select '29-02-1435', TO_DATE('29-92-1435', 'DD-MM-RRRR', 'nls_calendar=''English Hijrah''')
ERROR at line 1:
ORA-01843: not a valid month