Thrill  0.1
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Groups Pages
has_member.hpp
Go to the documentation of this file.
1 /*******************************************************************************
2  * tlx/meta/has_member.hpp
3  *
4  * Part of tlx - http://panthema.net/tlx
5  *
6  * Copyright (C) 2016-2017 Timo Bingmann <[email protected]>
7  *
8  * All rights reserved. Published under the Boost Software License, Version 1.0
9  ******************************************************************************/
10 
11 #ifndef TLX_META_HAS_MEMBER_HEADER
12 #define TLX_META_HAS_MEMBER_HEADER
13 
14 namespace tlx {
15 
16 //! \addtogroup tlx_meta
17 //! \{
18 
19 /******************************************************************************/
20 // SFINAE check whether a class member exists.
21 
22 // based on http://stackoverflow.com/questions/257288/is-it-possible
23 // -to-write-a-c-template-to-check-for-a-functions-existence
24 
25 /*!
26  * Macro template for class member / attribute SFINAE test
27 
28  Usage:
29  \code
30  TLX_MAKE_HAS_METHOD(myfunc);
31 
32  static_assert(has_method_myfunc<MyClass>::value,
33  "check MyClass for existence of attribute/method myfunc");
34  \endcode
35 */
36 #define TLX_MAKE_HAS_MEMBER(Member) \
37  template <typename Type> \
38  class has_member_ ## Member \
39  { \
40  template <typename C> \
41  static char test(decltype(&C::Member)); \
42  template <typename C> \
43  static int test(...); \
44  public: \
45  static const bool value = ( /* NOLINT */ \
46  sizeof(test<Type>(0)) == sizeof(char)); \
47  }
48 
49 /*!
50  * Macro template for class template member SFINAE test
51 
52  Usage:
53  \code
54  TLX_MAKE_HAS_TEMPLATE_METHOD(myfunc);
55 
56  static_assert(has_method_myfunc<MyClass, float, int>::value,
57  "check MyClass for existence of attribute/method myfunc "
58  "if instantiated with <float, int>");
59  \endcode
60 */
61 #define TLX_MAKE_HAS_TEMPLATE_MEMBER(Member) \
62  template <typename Type, typename... Args> \
63  class has_member_ ## Member \
64  { \
65  template <typename C> \
66  static char test(decltype(&C::template Member<Args...>)); \
67  template <typename C> \
68  static int test(...); \
69  public: \
70  static const bool value = ( /* NOLINT */ \
71  sizeof(test<Type>(0)) == sizeof(char)); \
72  }
73 
74 //! \}
75 
76 } // namespace tlx
77 
78 #endif // !TLX_META_HAS_MEMBER_HEADER
79 
80 /******************************************************************************/