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fix GetTextExtent with non-null font argument, fixes #13750
[wxWidgets.git] / interface / wx / scopeguard.h
1 /////////////////////////////////////////////////////////////////////////////
2 // Name: scopeguard.h
3 // Purpose: interface of global functions
4 // Author: wxWidgets team
5 // RCS-ID: $Id$
6 // Licence: wxWindows licence
7 /////////////////////////////////////////////////////////////////////////////
8
9 /**
10 @class wxScopeGuard
11
12 Scope guard is an object which allows executing an action on scope exit.
13
14 The objects of this class must be constructed using wxMakeGuard() function.
15
16 @nolibrary
17 @category{misc}
18 */
19 class wxScopeGuard
20 {
21 public:
22 /**
23 Call this method to dismiss the execution of the action on scope exit.
24
25 A typical example:
26 @code
27 Update1();
28
29 // ensure that changes done so far are rolled back if the next
30 // operation throws
31 wxScopeGuard guard = wxMakeGuard(RollBack);
32 Update2();
33
34 // it didn't throw so commit the changes, i.e. avoid rolling back
35 guard.Dismiss();
36 @endcode
37 */
38 void Dismiss();
39 };
40
41 /** @addtogroup group_funcmacro_misc */
42 //@{
43 /**
44 Returns a scope guard object which will call the specified function with
45 the given parameters on scope exit.
46
47 This function is overloaded to take several parameters up to some
48 implementation-defined (but relatively low) limit.
49
50 The @a func should be a functor taking parameters of the types P1, ..., PN,
51 i.e. the expression @c func(p1, ..., pN) should be valid.
52 */
53 template <typename F, typename P1, ..., typename PN>
54 wxScopeGuard wxMakeGuard(F func, P1 p1, ..., PN pN);
55
56 //@}
57
58 /** @addtogroup group_funcmacro_misc */
59 //@{
60 /**
61 Ensure that the global @a function with a few (up to some
62 implementation-defined limit) is executed on scope exit, whether due to a
63 normal function return or because an exception has been thrown.
64
65 A typical example of its usage:
66
67 @code
68 void *buf = malloc(size);
69 wxON_BLOCK_EXIT1(free, buf);
70 @endcode
71
72 Please see the original article by Andrei Alexandrescu and Petru Marginean
73 published in December 2000 issue of C/C++ Users Journal for more details.
74
75 @see wxON_BLOCK_EXIT_OBJ0()
76
77 @header{wx/scopeguard.h}
78 */
79 #define wxON_BLOCK_EXIT(function, ...)
80 #define wxON_BLOCK_EXIT0(function)
81 #define wxON_BLOCK_EXIT1(function, p1)
82 #define wxON_BLOCK_EXIT2(function, p1, p2)
83 #define wxON_BLOCK_EXIT3(function, p1, p2, p3)
84 //@}
85
86 /** @addtogroup group_funcmacro_misc */
87 //@{
88 /**
89 This family of macros is similar to wxON_BLOCK_EXIT(), but calls a method
90 of the given object instead of a free function.
91
92 @header{wx/scopeguard.h}
93 */
94 #define wxON_BLOCK_EXIT_OBJ(object, method, ...)
95 #define wxON_BLOCK_EXIT_OBJ0(object, method)
96 #define wxON_BLOCK_EXIT_OBJ1(object, method, p1)
97 #define wxON_BLOCK_EXIT_OBJ2(object, method, p1, p2)
98 #define wxON_BLOCK_EXIT_OBJ3(object, method, p1, p2, p3)
99 //@}
100
101 /** @addtogroup group_funcmacro_misc */
102 //@{
103 /**
104 This family of macros is similar to wxON_BLOCK_OBJ(), but calls a method
105 of @c this object instead of a method of the specified object.
106
107 @header{wx/scopeguard.h}
108 */
109 #define wxON_BLOCK_EXIT_THIS(method, ...)
110 #define wxON_BLOCK_EXIT_THIS0(method)
111 #define wxON_BLOCK_EXIT_THIS1(method, p1)
112 #define wxON_BLOCK_EXIT_THIS2(method, p1, p2)
113 #define wxON_BLOCK_EXIT_THIS3(method, p1, p2, p3)
114 //@}
115
116 /** @addtogroup group_funcmacro_misc */
117 //@{
118 /**
119 This macro sets a variable to the specified value on scope exit.
120
121 Example of usage:
122 @code
123 void foo()
124 {
125 bool isDoingSomething = true;
126 {
127 wxON_BLOCK_EXIT_SET(isDoingSomething, false);
128 ... do something ...
129 }
130 ... isDoingSomething is false now ...
131 }
132 @endcode
133
134 Notice that @a value is copied, i.e. stored by value, so it can be a
135 temporary object returned by a function call, for example.
136
137 @see wxON_BLOCK_EXIT_OBJ0(), wxON_BLOCK_EXIT_NULL()
138
139 @header{wx/scopeguard.h}
140 */
141 #define wxON_BLOCK_EXIT_SET(var, value)
142
143 /**
144 This macro sets the pointer passed to it as argument to NULL on scope exit.
145
146 It must be used instead of wxON_BLOCK_EXIT_SET() when the value being set
147 is @c NULL.
148
149 @header{wx/scopeguard.h}
150 */
151 #define wxON_BLOCK_EXIT_NULL(ptr)
152
153 //@}
154