有没有更好的方法来写这个模板？

问题描述：

我读谷歌C++测试框架上Github（https://github.com/google/googletest/blob/master/googletest/include/gtest/gtest-param-test.h）有没有更好的方法来写这个模板？

我发现作者写了下面的代码，

template <typename T1, typename T2, typename T3> 
internal::ValueArray3<T1, T2, T3> Values(T1 v1, T2 v2, T3 v3) { 
return internal::ValueArray3<T1, T2, T3>(v1, v2, v3); 
} 

template <typename T1, typename T2, typename T3, typename T4> 
internal::ValueArray4<T1, T2, T3, T4> Values(T1 v1, T2 v2, T3 v3, T4 v4) { 
return internal::ValueArray4<T1, T2, T3, T4>(v1, v2, v3, v4); 
} 
..... 
.... 
... 
.. 
. 
template <typename T1, typename T2, typename T3, typename T4, typename T5, 
typename T6, typename T7, typename T8, typename T9, typename T10, 
typename T11, typename T12, typename T13, typename T14, typename T15, 
typename T16, typename T17, typename T18, typename T19, typename T20, 
typename T21, typename T22, typename T23, typename T24, typename T25, 
typename T26, typename T27, typename T28, typename T29, typename T30, 
typename T31, typename T32, typename T33, typename T34, typename T35, 
typename T36, typename T37, typename T38, typename T39, typename T40, 
typename T41, typename T42, typename T43, typename T44, typename T45, 
typename T46, typename T47, typename T48, typename T49, typename T50> 
internal::ValueArray50<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, 
T14, T15, T16, T17, T18, T19, T20, T21, T22, T23, T24, T25, T26, T27, T28, 
T29, T30, T31, T32, T33, T34, T35, T36, T37, T38, T39, T40, T41, T42, T43, 
T44, T45, T46, T47, T48, T49, T50> Values(T1 v1, T2 v2, T3 v3, T4 v4, 
T5 v5, T6 v6, T7 v7, T8 v8, T9 v9, T10 v10, T11 v11, T12 v12, T13 v13, 
T14 v14, T15 v15, T16 v16, T17 v17, T18 v18, T19 v19, T20 v20, T21 v21, 
T22 v22, T23 v23, T24 v24, T25 v25, T26 v26, T27 v27, T28 v28, T29 v29, 
T30 v30, T31 v31, T32 v32, T33 v33, T34 v34, T35 v35, T36 v36, T37 v37, 
T38 v38, T39 v39, T40 v40, T41 v41, T42 v42, T43 v43, T44 v44, T45 v45, 
T46 v46, T47 v47, T48 v48, T49 v49, T50 v50) { 
return internal::ValueArray50<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, 
    T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22, T23, T24, T25, 
    T26, T27, T28, T29, T30, T31, T32, T33, T34, T35, T36, T37, T38, T39, 
    T40, T41, T42, T43, T44, T45, T46, T47, T48, T49, T50>(v1, v2, v3, v4, 
    v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, 
    v20, v21, v22, v23, v24, v25, v26, v27, v28, v29, v30, v31, v32, v33, 
    v34, v35, v36, v37, v38, v39, v40, v41, v42, v43, v44, v45, v46, v47, 
    v48, v49, v50); 
}

笔者花代码的数百行重载函数值为了从2到50参数列表。

我的问题是“是否有更好的方式来写它”？

谢谢。

- 一个C++ Noob。

“作者”似乎是一个代码生成器，而不是一个人。阅读文件中的注释：'这个文件是由命令产生的：pump.py gtest-param-test.h.pump不要用手编辑!!!'。 – PaulMcKenzie

您可以使用可变参数模板来更系统地表达这种情况，但代码可能希望可供C++ 98用户使用。 –

我明白了。感谢您指出它是由代码生成的。 – IceTeaCup

答

这在C++ 98/03中变得相当普遍。

从C++ 11开始，您通常会对可变参数模板做同样的事情。实际上，至少乍看起来，整个ValueArray可能非常接近C++ 11所谓的tuple。

有没有更好的方法来写这个模板？

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