模板中非类型参数的限制

C/C++ code

//函数模板定义：template <ofstream &of,class T>ofstream &func(T t){    of<<t<<endl;    return of;                                }//of定义为全局变量：ofstream of("out.txt");//调用时,即将5输入到文件中！func<of,int>(5);

关于of的问题，查资料说 ：非类型参数必须在编译时就确定其值，但是我将of在main函数中定义为static ofstream of("out.txt")；或者定义为全局的static ofstream of("out.txt")都会出问题！
赐教！！

[解决办法]
除整形以外，其他的不要作为非类型模板参数。
[解决办法]
14.3.2 Template non-type arguments [temp.arg.nontype]
1 A template-argument for a non-type, non-template template-parameter shall be one of:
— an integral constant-expression of integral or enumeration type; or
— the name of a non-type template-parameter; or
— the address of an object or function with external linkage, including function templates and function
template-ids but excluding non-static class members, expressed as & id-expression where the & is
optional if the name refers to a function or array, or if the corresponding template-parameter is a reference;
or
— a pointer to member expressed as described in 5.3.1 .


external linkage 知道什么意思吧?