Re: [Boost-users] How to write a predicate for mpl::find_if that is able to work with placeholders?

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I solved it. I crawled through the mpl sources (not an easy task) and found how it has to work. The predicate needs to be defined as: template struct contained { static const int value=is_same::value; template struct apply; };

template<int i> struct Slot { typedef Slot type; typedef int_<i> slot_id; }; typedef vector, Slot<10>, Slot<15> > slots; typedef find_if > >::type t10; BOOST_MPL_ASSERT(( is_same< deref<t10>::type, Slot<10> > ));

This works as intended. However, finding out how to write such a predicate, was very hard. Providing examples, describing the different kinds of predicates and how they need to be written in order to work with placeholders, would be very helpful. Maybe such things could be added to the mpl documentation, because I am sure, I am not the first that came up with such an issue. Regards, Michael -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJMmP6eAAoJEKn9/33w5fU9FQAH/0gzuptHEBfAqfkVrmjD3/+X ibhtkSMCyXarkTSbTLYeJ7mOZ7cZ9hMpa2pLvQG0W6jLFvyjVnL+zJDrIbNFDFs9 ++nIzlijFqnaVSqi8WRAw5mXn9Ai2j0NFRyBDz70N+fPFkm+KsRDyL6pME6oLI+u WDRG4jexnLeomrIePrWbTdpNQaTKerp91cnR/6wJdMNBgDxePnP9Yzye5ltPsJzi H7SpqqHpX9yXxslvMi7vN7V8qrPwHx1Y17ILzIP77/EA/hBpFkcxPC8H8YdoUF9n UxIJ5RGwq54bEgF8qvVKkZsZy8s5u42H3E+rbNxmUcoQmaQ+Ow7gvEzQqVJTbHI= =siFh -----END PGP SIGNATURE-----