带有嵌套模板的C ++ typedef不是类，结构或联合类型

Question

我不确定为什么不使用g ++编译以下代码：

t.cpp: In instantiation of ‘Distrib<double>’:
t.cpp:28:56:   instantiated from ‘Sampler<Distrib<Solution<double> > >’
t.cpp:35:48:   instantiated from here
t.cpp:16:45: erreur: ‘double’ is not a class, struct, or union type
t.cpp:18:43: erreur: ‘double’ is not a class, struct, or union type

我期望能够AtomType在嵌套模板之间传播类型……

t.cpp: In instantiation of ‘Distrib<double>’:
t.cpp:28:56:   instantiated from ‘Sampler<Distrib<Solution<double> > >’
t.cpp:35:48:   instantiated from here
t.cpp:16:45: erreur: ‘double’ is not a class, struct, or union type
t.cpp:18:43: erreur: ‘double’ is not a class, struct, or union type

Answer 1

在你的Sampler班级里，你有：

typedef typename Distrib<AtomType>::Matrix Matrix;

这里，AtomType是double，所以这是

typedef typename Distrib<double>::Matrix Matrix;

然后在你的Distrib课堂上，这条线

typedef typename SOLT::AtomType AtomType;

扩展到

typedef typename double::AtomType AtomType;

因此出现错误消息。我想你希望课堂上的线路Sampler是：

typedef typename DT::Matrix Matrix;