C++核心準則ES.7: 通用和局部的名稱應該簡短,特殊和非局部的名稱...

ES.7: Keep common and local names short, and keep uncommon and non-local names longer

ES.7: 通用和局部的名稱應該簡短，特殊和非局部的名稱應該較長。

Reason（原因）

Readability. Lowering the chance of clashes between unrelated non-local names.

可讀性。避免無關的非局部名稱之間的沖突。

Example（示例）

Conventional short, local names increase readability:

遵循慣例的，簡短的局部變量可以增加可讀性。

template    // good
void print(ostream& os, const vector& v)
{
    for (gsl::index i = 0; i < v.size(); ++i)
        os << v[i] << '\n';
}

An index is conventionally called?i?and there is no hint about the meaning of the vector in this generic function, so?v?is as good name as any. Compare

索引習慣上命名為i；在這個通用函數(shù)中，關于vector的含義沒有任何參考信息，因此v也是一個好名字。

template   // bad: verbose, hard to read
void print(ostream& target_stream, const vector& current_vector)
{
    for (gsl::index current_element_index = 0;
         current_element_index < current_vector.size();
         ++current_element_index
    )
    target_stream << current_vector[current_element_index] << '\n';
}

Yes, it is a caricature, but we have seen worse.

是的，這段代碼有點夸張，但是我們確實看過更差的。

Example（示例）

Unconventional and short non-local names obscure code:

特殊且很短的非局部名稱會擾亂代碼：

void use1(const string& s)
{
    // ...
    tt(s);   // bad: what is tt()?
    // ...
}

Better, give non-local entities readable names:

稍好一點的做法是，為非局部實體提供可讀的名稱：

void use1(const string& s)
{
    // ...
    trim_tail(s);   // better
    // ...
}

Here, there is a chance that the reader knows what?trim_tail?means and that the reader can remember it after looking it up.

存在這樣的可能性：讀者能夠理解trim_tail的含義并且可以在查閱代碼之后能夠記住它。

Example, bad（反面示例）

Argument names of large functions are de facto non-local and should be meaningful:

長函數(shù)的參數(shù)名屬于事實上的非局部變量，應該具有明確的含義：

void complicated_algorithm(vector& vr, const vector& vi, map& out)
// read from events in vr (marking used Records) for the indices in
// vi placing (name, index) pairs into out
{
    // ... 500 lines of code using vr, vi, and out ...
}

We recommend keeping functions short, but that rule isn't universally adhered to and naming should reflect that.

我們推薦保持函數(shù)簡短，但是該規(guī)則不會適用于所有情況，名稱也應該反映這種變化。

Enforcement（實施建議）

Check length of local and non-local names. Also take function length into account.

檢查局部和非局部變量的長度。注意同時考慮函數(shù)的長度。

原文鏈接

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#es7-keep-common-and-local-names-short-and-keep-uncommon-and-non-local-names-longer

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