#define <宏名> (<参数表>) <宏体>
#undef <宏名>
#ifdef <宏名>
...
#else
...
#endif
//define中的三个特殊符号:#,##,#@
#define STRCAT(x,y) x##y //连接x和y成一个字符串
#define TOCHAR(x) #@x //给x加上单引号
#define TOSTR(x) #x //给x加上双引号
宏是C/C++系列语言的一大特色,它将一个标识符定义为一个字符串,在预处理阶段源程序中的该标识符均以指定的字符串来代替,使用宏可以使代码更加简洁和增强可读性。
操作系统宏、处理器相关宏、编译器宏
#define Q_OS_X // 例如 Q_OS_WIN
#deinfe Q_PROCESSOR_X // 例如 Q_PROCESSOR_X86_32
#define Q_BYTE_ORDER Q_LITTLE_ENDIAN // 字节序:小端模式
#define Q_PROCESSOR_WORDSIZE 4
#define Q_CC_X // 例如 Q_CC_MINGW
动态库宏
#ifdef Q_OS_WIN
#define Q_DECL_EXPORT __declspec(dllexport)
#define Q_DECL_IMPORT __declspec(dllimport)
#endif
命名空间宏
#define QT_USE_NAMESPACE using namespace ::QT_NAMESPACE;
#define QT_BEGIN_NAMESPACE namespace QT_NAMESPACE {
#define QT_END_NAMESPACE }
Qt注释宏(注释类、函数、访问限制符)
#define QT_ANNOTATE_CLASS(type, ...)
#define QT_ANNOTATE_FUNCTION(x)
#define QT_ANNOTATE_ACCESS_SPECIFIER(x)
Qt信号与槽机制相关宏
#define slots Q_SLOTS
#define signals Q_SIGNALS
#define emit
#define Q_SLOTS QT_ANNOTATE_ACCESS_SPECIFIER(qt_slot)
#define Q_SIGNALS public QT_ANNOTATE_ACCESS_SPECIFIER(qt_signal)
#define Q_EMIT
#define METHOD(a) qFlagLocation("0"#a QLOCATION)
#define SLOT(a) qFlagLocation("1"#a QLOCATION)
#define SIGNAL(a) qFlagLocation("2"#a QLOCATION)
const char *qFlagLocation(const char *method)
{
QThreadData *currentThreadData = QThreadData::current(false);
if (currentThreadData != 0)
currentThreadData->flaggedSignatures.store(method);
return method;
}
可以分析出signals限定了是public的,而发射信号emit就是调用信号函数
而我们在连接信号与槽时使用的SIGNAL和SLOT,就是一个代表方法的字符串
Qt类相关宏
#define Q_CLASSINFO(name, value)
#define Q_PLUGIN_METADATA(x) QT_ANNOTATE_CLASS(qt_plugin_metadata, x)
#define Q_INTERFACES(x) QT_ANNOTATE_CLASS(qt_interfaces, x)
#ifdef Q_COMPILER_VARIADIC_MACROS
# define Q_PROPERTY(...) QT_ANNOTATE_CLASS(qt_property, __VA_ARGS__)
#else
# define Q_PROPERTY(text) QT_ANNOTATE_CLASS(qt_property, text)
#endif
#define Q_PRIVATE_PROPERTY(d, text) QT_ANNOTATE_CLASS2(qt_private_property, d, text)
#ifndef Q_REVISION
# define Q_REVISION(v)
#endif
#define Q_OVERRIDE(text) QT_ANNOTATE_CLASS(qt_override, text)
#define QDOC_PROPERTY(text) QT_ANNOTATE_CLASS(qt_qdoc_property, text)
#define Q_ENUMS(x) QT_ANNOTATE_CLASS(qt_enums, x)
#define Q_FLAGS(x) QT_ANNOTATE_CLASS(qt_enums, x)
#define Q_ENUM_IMPL(ENUM) \
friend Q_DECL_CONSTEXPR const QMetaObject *qt_getEnumMetaObject(ENUM) Q_DECL_NOEXCEPT { return &staticMetaObject; } \
friend Q_DECL_CONSTEXPR const char *qt_getEnumName(ENUM) Q_DECL_NOEXCEPT { return #ENUM; }
#define Q_ENUM(x) Q_ENUMS(x) Q_ENUM_IMPL(x)
#define Q_FLAG(x) Q_FLAGS(x) Q_ENUM_IMPL(x)
#define Q_SCRIPTABLE QT_ANNOTATE_FUNCTION(qt_scriptable)
#define Q_INVOKABLE QT_ANNOTATE_FUNCTION(qt_invokable)
#define Q_SIGNAL QT_ANNOTATE_FUNCTION(qt_signal)
#define Q_SLOT QT_ANNOTATE_FUNCTION(qt_slot)
其中Q_PROPERTY定义了Qt的属性系统,Q_ENUMS、Q_FLAGS定义了Qt的枚举类型操作
Qt翻译宏
#define QT_TR_FUNCTIONS \
static inline QString tr(const char *s, const char *c = Q_NULLPTR, int n = -1) \
{ return staticMetaObject.tr(s, c, n); } \
QT_DEPRECATED static inline QString trUtf8(const char *s, const char *c = Q_NULLPTR, int n = -1) \
{ return staticMetaObject.tr(s, c, n); }
Q_OBJECT宏
#define Q_OBJECT \
public: \
static const QMetaObject staticMetaObject; \
virtual const QMetaObject *metaObject() const; \
virtual void *qt_metacast(const char *); \
virtual int qt_metacall(QMetaObject::Call, int, void **); \
QT_TR_FUNCTIONS \
private: \
static void qt_static_metacall(QObject *, QMetaObject::Call, int, void **);
Q_OBJECT宏是Qt元对象模型Meta-Object Model的基础