C++ Templates中的例子编译不过的原因

    此例子来源于《C++Templates The Complete Guide》，
    使用了两种编译器(gcc 3.4.4, Dev-C++ 4.9.9.2)，都出现如下错误：

    C++ Templates中的functor源代码。编译其中的一个cpp文件（compose6.cpp）即可。
    下载地址：
    http://www.josuttis.com/tmplbook/examples.zip

    编译错误：
    dell@dell-PC /cygdrive/g/cyghome/src/cpptemplates/functors $ make g++.exe  compose6.cpp -o test.exe
    In file included from forwardparam.hpp:15,
                     from functionptr.hpp:11,
                     from funcptr.hpp:11,
                     from compose6.cpp:12:
    typet.hpp:73: error: expected primary-expression before '>' token
    typet.hpp: In instantiation of `IsFunctionT<double>':
    typet.hpp:105:   instantiated from `CompoundT<double>'
    typet.hpp:290:   instantiated from `TypeT<double>'
    forwardparam.hpp:29:   instantiated from `ForwardParamT<double>'
    functionptr.hpp:39:   instantiated from `FunctionPtr<double, double, double, voi
    d>'
    compose6.cpp:29:   instantiated from here
    typet.hpp:73: error: enumerator value for `Yes' not integer constant
    make: *** [test.exe] Error 1

    解决方法：去掉IsFunctionT<T>::