\section{Alphabetical functions and macros list}
\helpref{CLASSINFO}{classinfo}\\
+\helpref{copystring}{copystring}\\
\helpref{DECLARE\_ABSTRACT\_CLASS}{declareabstractclass}\\
\helpref{DECLARE\_APP}{declareapp}\\
\helpref{DECLARE\_CLASS}{declareclass}\\
\helpref{WXDEBUG\_NEW}{debugnew}\\
\helpref{WXTRACELEVEL}{tracelevel}\\
\helpref{WXTRACE}{trace}\\
-\helpref{copystring}{copystring}\\
+\helpref{wxASSERT\_MIN\_BITSIZE}{wxassertminbitsize}\\
\helpref{wxASSERT\_MSG}{wxassertmsg}\\
\helpref{wxASSERT}{wxassert}\\
\helpref{wxBITMAP}{wxbitmapmacro}\\
\helpref{wxClipboardOpen}{wxclipboardopen}\\
\helpref{wxCloseClipboard}{wxcloseclipboard}\\
\helpref{wxColourDisplay}{wxcolourdisplay}\\
+\helpref{wxCOMPILE\_TIME\_ASSERT}{wxcompiletimeassert}\\
\helpref{wxConcatFiles}{wxconcatfiles}\\
\helpref{wxConstCast}{wxconstcast}\\
\helpref{wxCopyFile}{wxcopyfile}\\
\section{Debugging macros and functions}\label{debugmacros}
-Useful macros and functions for error checking and defensive programming. ASSERTs are only
-compiled if \_\_WXDEBUG\_\_ is defined, whereas CHECK macros stay in release
-builds.
+Useful macros and functions for error checking and defensive programming.
+wxWindows defines three families of the assert-like macros:
+the wxASSERT and wxFAIL macros only do anything if \_\_WXDEBUG\_\_ is defined
+(in other words, in the debug build) but disappear completely in the release
+build. On the other hand, the wxCHECK macros stay event in release builds but a
+check failure doesn't generate any user-visible effects then. Finally, the
+compile time assertions don't happen during the run-time but result in the
+compilation error messages if the condition they check fail.
\wxheading{Include files}
\func{void}{wxOnAssert}{\param{const char *}{fileName}, \param{int}{ lineNumber}, \param{const char *}{msg = NULL}}
-This function may be redefined to do something non trivial and is called
-whenever one of debugging macros fails (i.e. condition is false in an
-assertion).
-% TODO: this should probably be an overridable in wxApp.
+This function is called whenever one of debugging macros fails (i.e. condition
+is false in an assertion). It is only defined in the debug mode, in release
+builds the \helpref{wxCHECK}{wxcheck} failures don't result in anything.
+
+To override the default behaviour in the debug builds which is to show the user
+a dialog asking whether he wants to abort the program, continue or continue
+ignoring any subsequent assert failures, you may override
+\helpref{wxApp::OnAssert}{wxapponassert} which is called by this function if
+the global application object exists.
\membersection{wxASSERT}\label{wxassert}
Please note that the condition in wxASSERT() should have no side effects
because it will not be executed in release mode at all.
-See also: \helpref{wxASSERT\_MSG}{wxassertmsg}
+\wxheading{See also}
+
+\helpref{wxASSERT\_MSG}{wxassertmsg},\\
+\helpref{wxCOMPILE\_TIME\_ASSERT}{wxcompiletimeassert}
+
+\membersection{wxASSERT\_MIN\_BITSIZE}\label{wxassertminbitsize}
+
+\func{}{wxASSERT\_MIN\_BITSIZE}{\param{}{type}, \param{}{size}}
+
+This macro results in a
+\helpref{compile time assertion failure}{wxCOMPILE\_TIME\_ASSERT} if the size
+of the given type {\it type} is less than {\it size} bits.
+
+You may use it like this, for example:
+
+\begin{verbatim}
+ // we rely on the int being able to hold values up to 2^32
+ wxASSERT_MIN_BITSIZE(int, 32);
+
+ // can't work with the platforms using UTF-8 for wchar_t
+ wxASSERT_MIN_BITSIZE(wchar_t, 16);
+\end{verbatim}
\membersection{wxASSERT\_MSG}\label{wxassertmsg}
Assert macro with message. An error message will be generated if the condition is FALSE.
-See also: \helpref{wxASSERT}{wxassert}
+\wxheading{See also}
+
+\helpref{wxASSERT}{wxassert},\\
+\helpref{wxCOMPILE\_TIME\_ASSERT}{wxcompiletimeassert}
+
+\membersection{wxCOMPILE\_TIME\_ASSERT}\label{wxcompiletimeassert}
+
+\func{}{wxCOMPILE\_TIME\_ASSERT}{\param{}{condition}, \param{}{msg}}
+
+Using {\tt wxCOMPILE\_TIME\_ASSERT} results in a compilation error if the
+specified {\it condition| is false. The compiler error message should include
+the {\it msg} identifier - please note that it must be a valid C++ identifier
+and not a string unlike in the other cases.
+
+This macro is mostly useful for testing the expressions involing the
+{\tt sizeof} operator as they can't be tested by the preprocessor but it is
+sometimes desirable to test them at the compile time.
+
+\wxheading{See also}
+
+\helpref{wxASSERT\_MSG}{wxassertmsg},\\
+\helpref{wxASSERT\_MIN\_BITSIZE}{wxassertminbitsize}
\membersection{wxFAIL}\label{wxfail}
it may be used in the "default:" branch of a switch statement if all possible
cases are processed above.
-See also: \helpref{wxFAIL}{wxfail}
+\wxheading{See also}
+
+\helpref{wxFAIL}{wxfail}
\membersection{wxCHECK}\label{wxcheck}
#define _WX_DEBUG_H_
#include <assert.h>
+#include <limits.h> // for CHAR_BIT used below
-#include "wx/wxchar.h"
+#include "wx/wxchar.h" // for __TFILE__ and wxChar
// ----------------------------------------------------------------------------
// Defines controlling the debugging macros
// to begin with...)
#define wxCHECK_RET(x, msg) if (!(x)) {wxFAIL_MSG(msg); return; }
+// ----------------------------------------------------------------------------
+// Compile time asserts
+//
+// Unlike the normal assert and related macros above which are checked during
+// the program tun-time the macros below will result in a compilation error if
+// the condition they check is false. This is usually used to check the
+// expressions containing sizeof()s which cannot be tested with the
+// preprocessor. If you can use the #if's, do use them as you can give a more
+// detailed error message then.
+// ----------------------------------------------------------------------------
+
+/*
+ How this works (you don't have to understand it to be able to use the
+ macros): we rely on the fact that it is invalid to define a named bit field
+ in a struct of width 0. All the rest are just the hacks to minimize the
+ possibility of the compiler warnings when compiling this macro: in
+ particular, this is why we define a struct and not an object (which would
+ result in a warning about unused variable) and a named struct (otherwise we'd
+ get a warning about an unnamed struct not used to define an object!).
+ */
+
+#define wxMAKE_ASSERT_NAME_HELPER(line) wxAssert_ ## line
+#define wxMAKE_ASSERT_NAME(line) wxMAKE_ASSERT_NAME_HELPER(line)
+#define wxMAKE_UNIQUE_ASSERT_NAME wxMAKE_ASSERT_NAME(__LINE__)
+
+/*
+ The second argument of this macro must be a valid C++ identifier and not a
+ string. I.e. you should use it like this:
+
+ wxCOMPILE_TIME_ASSERT( sizeof(int) >= 2, YourIntsAreTooSmall );
+
+ It may be used both within a function and in the global scope.
+*/
+#define wxCOMPILE_TIME_ASSERT(expr, msg) \
+ struct wxMAKE_UNIQUE_ASSERT_NAME { unsigned int msg: expr; }
+
+// helpers for wxCOMPILE_TIME_ASSERT below, for private use only
+#define wxMAKE_BITSIZE_MSG(type, size) type ## SmallerThan ## size ## Bits
+
+// a special case of compile time assert: check that the size of the given type
+// is at least the given number of bits
+#define wxASSERT_MIN_BITSIZE(type, size) \
+ wxCOMPILE_TIME_ASSERT(sizeof(type) * CHAR_BIT >= size, \
+ wxMAKE_BITSIZE_MSG(type, size))
+
#endif // _WX_DEBUG_H_
projects / wxWidgets.git / commitdiff
