Public mpz_ptr and mpz_srcptr
nisse at lysator.liu.se
Mon Feb 4 18:00:43 CET 2013
Torbjorn Granlund <tg at gmplib.org> writes:
> The intended way of returning mpz_t variables is doing it like GMP does,
> i.e., pass the destination mpz_t variables as parameters.
Sure, that the *usual* way for a function that modifies the number.
"Make the common case easy, and the uncommon case possible..."
Here's another possible use of mpz pointers:
foo (mpz_srcptr a, mpz_srcptr b)
/* Make a <= b */
if (mpz_cmp (a, b) > 0)
mpz_srcptr t = a;
a = b;
b = t;
... further computation on a and b ...
I think this is perfectly reasonable user code. And note in particular
that if the user tried mpz_swap instead, she would be shooting herself
badly in the foot.
I think using typedefed arrays in C (like mpz_t) is a hack which has to
be used with extreme care in special circumstances (and GMP may be a
valid use). Then it's pretty evil of an API to not provide *any* public
types for its abstractions, except for array typedefs.
Niels Möller. PGP-encrypted email is preferred. Keyid C0B98E26.
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