Qt源码中的Template模板用法.ppt

* Qt源码中的C++ Template 用法 yoyo,2015 Review of C++ Template Syntax Qt Template MetaProgramming C++ Template usage in Qt 1 2 3 一般用法 Review of C++ Template Syntaxyntax // 一个简单的加法模板 templateclass T class Addition { public: T fun( T a, T b ) { return ( a + b ); } }; specialization Review of C++ Template Syntaxyntax template class Additionchar * { public: char * fun( char * a, char * b ) { ... strcat_s(... ); return a; } }; Partial specialization Review of C++ Template Syntaxyntax /* ** 特化为引用，指针类型 ** 偏特化，半特化，局部特化，部分特化 ** 在编码时，总纠结着是指针好呢，还是引用好呢，要加const？ ** 有了这样的特化，确实方便甚多。 */ templateclass T class AdditionT { public: T fun( T a, T b ) { a = a + b; return a; } }; 编译期类型推断 Qt Templatetax /* quintptr and qptrdiff is guaranteed to be the same size as a pointer, i.e. sizeof(void *) == sizeof(quintptr) sizeof(void *) == sizeof(qptrdiff) */ template int struct QIntegerForSize; template struct QIntegerForSize1 { typedef quint8 Unsigned; typedef qint8 Signed; }; template struct QIntegerForSize2 { typedef quint16 Unsigned; typedef qint16 Signed; }; template struct QIntegerForSize4 { typedef quint32 Unsigned; typedef qint32 Signed; }; template struct QIntegerForSize8 { typedef quint64 Unsigned; typedef qint64 Signed; }; template class T struct QIntegerForSizeof : QIntegerForSizesizeof(T) { }; typedef QIntegerForSizeofvoid*::Unsigned quintptr; typedef QIntegerForSizeofvoid*::Signed qptrdiff; QT Assistant 的文档 Qt Templatetax typedef quintptr Integral type for representing a pointers (useful for hashing, etc.). Typedef for either quint32 or quint64. This type is guaranteed to be the same size as a pointer on all platforms supported by Qt. On a system with 32-bit pointers, quintptr is a typedef for quint32; on a system with 64-bit pointers, quintptr is a typedef for quint64. Note that quintptr is unsigned. Use qptrdiff for sig