| .. Metafunctions/Miscellaneous//inherit |30 |
| |
| inherit |
| ======= |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| template< |
| typename T1, typename T2 |
| > |
| struct inherit\ ``2`` |
| { |
| typedef |unspecified| type; |
| }; |
| |
| |...| |
| |
| template< |
| typename T1, typename T2,\ |...| typename T\ *n* |
| > |
| struct inherit\ *n* |
| { |
| typedef |unspecified| type; |
| }; |
| |
| template< |
| typename T1 |
| , typename T2 |
| |...| |
| , typename T\ *n* = |unspecified| |
| > |
| struct inherit |
| { |
| typedef |unspecified| type; |
| }; |
| |
| |
| Description |
| ----------- |
| |
| Returns an unspecified class type publically derived from |T1...Tn|. |
| Guarantees that derivation from |empty_base| is always a no-op, |
| regardless of the position and number of |empty_base| classes in |
| |T1...Tn|. |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/inherit.hpp> |
| |
| |
| Model of |
| -------- |
| |
| |Metafunction| |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+-------------------+-----------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===================+===================================+ |
| | |T1...Tn| | A class type | Classes to derived from. | |
| +---------------+-------------------+-----------------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| For artibrary class types |t1...tn|: |
| |
| .. parsed-literal:: |
| |
| typedef inherit2<t1,t2>::type r; |
| |
| :Return type: |
| A class type. |
| |
| :Precondition: |
| ``t1`` and ``t2`` are complete types. |
| |
| :Semantics: |
| If both ``t1`` and ``t2`` are identical to ``empty_base``, equivalent to |
| |
| .. parsed-literal:: |
| |
| typedef empty_base r; |
| |
| |
| otherwise, if ``t1`` is identical to ``empty_base``, equivalent to |
| |
| .. parsed-literal:: |
| |
| typedef t2 r; |
| |
| |
| otherwise, if ``t2`` is identical to ``empty_base``, equivalent to |
| |
| .. parsed-literal:: |
| |
| typedef t1 r; |
| |
| |
| otherwise equivalent to |
| |
| .. parsed-literal:: |
| |
| struct r : t1, t2 {}; |
| |
| .. ........................................................................... |
| |
| .. parsed-literal:: |
| |
| typedef inherit\ *n*\<t1,t2,\ |...|\ t\ *n*\ >::type r; |
| |
| :Return type: |
| A class type. |
| |
| :Precondition: |
| |t1...tn| are complete types. |
| |
| :Semantics: |
| Equivalent to |
| |
| .. parsed-literal:: |
| |
| struct r |
| : inherit\ ``2``\< |
| inherit\ *n-1*\<t1,t2,\ |...|\ t\ *n-1*\>::type |
| , t\ *n* |
| > |
| { |
| }; |
| |
| |
| .. ........................................................................... |
| |
| |
| .. parsed-literal:: |
| |
| typedef inherit<t1,t2,\ |...|\ t\ *n*\ >::type r; |
| |
| :Precondition: |
| |t1...tn| are complete types. |
| |
| :Return type: |
| A class type. |
| |
| :Semantics: |
| Equivalent to |
| |
| .. parsed-literal:: |
| |
| typedef inherit\ *n*\<t1,t2,\ |...|\ t\ *n*\ >::type r; |
| |
| |
| |
| Complexity |
| ---------- |
| |
| Amortized constant time. |
| |
| |
| Example |
| ------- |
| |
| .. parsed-literal:: |
| |
| struct udt1 { int n; }; |
| struct udt2 {}; |
| |
| typedef inherit<udt1,udt2>::type r1; |
| typedef inherit<empty_base,udt1>::type r2; |
| typedef inherit<empty_base,udt1,empty_base,empty_base>::type r3; |
| typedef inherit<udt1,empty_base,udt2>::type r4; |
| typedef inherit<empty_base,empty_base>::type r5; |
| |
| BOOST_MPL_ASSERT(( is_base_and_derived< udt1, r1> )); |
| BOOST_MPL_ASSERT(( is_base_and_derived< udt2, r1> )); |
| BOOST_MPL_ASSERT(( is_same< r2, udt1> )); |
| BOOST_MPL_ASSERT(( is_same< r3, udt1 > )); |
| BOOST_MPL_ASSERT(( is_base_and_derived< udt1, r4 > )); |
| BOOST_MPL_ASSERT(( is_base_and_derived< udt2, r4 > )); |
| BOOST_MPL_ASSERT(( is_same< r5, empty_base > )); |
| |
| |
| See also |
| -------- |
| |
| |Metafunctions|, |empty_base|, |inherit_linearly|, |identity| |
| |
| |
| .. copyright:: Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |