C++核心準(zhǔn)則C.52:合理使用繼承的構(gòu)造函數(shù)

C.52: Use inheriting constructors to import constructors into a derived class that does not need further explicit initialization
C.52:使用繼承的構(gòu)造函數(shù)功能將構(gòu)造函數(shù)導(dǎo)入不再需要進(jìn)一步明確初始化的派生類(lèi)

Reason（原因）

If you need those constructors for a derived class, re-implementing them is tedious and error-prone.

如果派生類(lèi)需要那些構(gòu)造函數(shù)，重新實(shí)現(xiàn)它們的工作單調(diào)乏味而且容易發(fā)生錯(cuò)誤。

Example（示例）

std::vector has a lot of tricky constructors, so if I want my own vector, I don't want to reimplement them:

std::vector有大量的構(gòu)造函數(shù)很難用，因此如果我需要自己的vector，我不會(huì)重新實(shí)現(xiàn)它們。

class Rec {
 ? ?// ... data and lots of nice constructors ...
};

class Oper : public Rec {
 ? ?using Rec::Rec;
 ? ?// ... no data members ...
 ? ?// ... lots of nice utility functions ...
};

Example, bad（反面示例）

struct Rec2 : public Rec {
 ? ?int x;
 ? ?using Rec::Rec;
};

Rec2 r {"foo", 7};
int val = r.x; ? // uninitialized

這就是需要進(jìn)一步初始化的例子。如果派生類(lèi)沒(méi)有增加數(shù)據(jù)成員只是增加一些功能，就可以使用using Rec::Rec這種方法導(dǎo)入基類(lèi)的構(gòu)造函數(shù)。對(duì)于上面的例子也可以考慮使用類(lèi)內(nèi)初始化器初始化數(shù)據(jù)成員x。

Enforcement

Make sure that every member of the derived class is initialized.

保證派生類(lèi)的所有成員都被初始化。

原文鏈接

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c52-use-inheriting-constructors-to-import-constructors-into-a-derived-class-that-does-not-need-further-explicit-initialization

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