Qt源码中的Template模板用法.ppt

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1、Qt源码中的C++Template用法yoyo,2015ReviewofC++TemplateSyntaxQtTemplateMetaProgrammingC++TemplateusageinQt123一般用法ReviewofC++TemplateSyntaxyntax//一个简单的加法模板templateclassAddition{public:Tfun(Ta,Tb){return(a+b);}};specializationReviewofC++TemplateSyntaxyntaxtemplate<>classAddition{public:char*fu

2、n(char*a,char*b){...strcat_s(...);returna;}};PartialspecializationReviewofC++TemplateSyntaxyntax/***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。*/templateclassAddition{public:T&fun(T&a,T&b){a=a+b;returna;}};编译期类型推断QtTemplatetax/*quintptrandqptrdiffisgua

3、ranteedtobethesamesizeasapointer,i.e.sizeof(void*)==sizeof(quintptr)&&sizeof(void*)==sizeof(qptrdiff)*/templatestructQIntegerForSize;template<>structQIntegerForSize<1>{typedefquint8Unsigned;typedefqint8Signed;};template<>structQIntegerForSize<2>{typedefquint16Unsigned;typedefqint16Signed;};tem

4、plate<>structQIntegerForSize<4>{typedefquint32Unsigned;typedefqint32Signed;};template<>structQIntegerForSize<8>{typedefquint64Unsigned;typedefqint64Signed;};templatestructQIntegerForSizeof:QIntegerForSize{};typedefQIntegerForSizeof::Unsignedquintptr;typedefQIntegerForSizeo

5、f::Signedqptrdiff;QTAssistant的文档QtTemplatetaxtypedefquintptrIntegraltypeforrepresentingapointers(usefulforhashing,etc.).Typedefforeitherquint32orquint64.ThistypeisguaranteedtobethesamesizeasapointeronallplatformssupportedbyQt.Onasystemwith32-bitpointers,quintptrisatypedefforquint32;onasystem

6、with64-bitpointers,quintptrisatypedefforquint64.Notethatquintptrisunsigned.Useqptrdiffforsignedvalues.Seealsoqptrdiff,quint32,andquint64.typedefQIntegerForSizeof::Signedqptrdiff;QTypeInfo-typetrait（=feature，quality）QtTemplatetax/*QTypeInfo-typetraitfunctionalityqIsDetached-datasharingfunctio

7、nality*//*Thecatch-alltemplate.*/templateinlineboolqIsDetached(T&){returntrue;}templateclassQTypeInfo{public:enum{isPointer=false,isComplex=true,isStatic=true,isLarge=(sizeof(T)>sizeof