C++核心準(zhǔn)則ES.2: 適當(dāng)?shù)某橄蠛糜谥苯邮褂谜Z言功能

ES.2: Prefer suitable abstractions to direct use of language features

ES.2: 適當(dāng)?shù)某橄蠛糜谥苯邮褂谜Z言功能

Reason（原因）

A "suitable abstraction" (e.g., library or class) is closer to the application concepts than the bare language, leads to shorter and clearer code, and is likely to be better tested.

“適當(dāng)?shù)某橄蟆保ɡ鐜旎蝾悾┍戎苯邮褂谜Z言功能更接近應(yīng)用概念，這會帶來更短、更清晰的代碼，很有可能被更好地測試。

Example（示例）

vector read1(istream& is)   // good
{
    vector res;
    for (string s; is >> s;)
        res.push_back(s);
    return res;
}

The more traditional and lower-level near-equivalent is longer, messier, harder to get right, and most likely slower:

更加傳統(tǒng)的、低層次的差不多等價的代碼會更長，更亂，更難保證正確性，而且很有可能更慢。

char** read2(istream& is, int maxelem, int maxstring, int* nread)   // bad: verbose and incomplete
{
    auto res = new char*[maxelem];
    int elemcount = 0;
    while (is && elemcount < maxelem) {
        auto s = new char[maxstring];
        is.read(s, maxstring);
        res[elemcount++] = s;
    }
    nread = &elemcount;
    return res;
}

Once the checking for overflow and error handling has been added that code gets quite messy, and there is the problem remembering to?delete?the returned pointer and the C-style strings that array contains.

一旦增加了溢出檢查，錯誤處理，代碼會變得很亂，而且還存在需要記住銷毀返回的指針和數(shù)組包含的C風(fēng)格字符串的問題。

Enforcement（實施建議）

Not easy. ??? Look for messy loops, nested loops, long functions, absence of function calls, lack of use of non-built-in types. Cyclomatic complexity?

不容易，不容易。尋找混亂的循環(huán)、嵌套循環(huán)、長函數(shù)、函數(shù)調(diào)用缺失、很少被使用的內(nèi)置類型？還是確認(rèn)圈復(fù)雜度？

原文鏈接

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#es2-prefer-suitable-abstractions-to-direct-use-of-language-features

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