[format.formatter.locking]

# 28 Text processing library [[text]](./#text)

## 28.5 Formatting [[format]](format#formatter.locking)

### 28.5.6 Formatter [[format.formatter]](format.formatter#locking)

#### 28.5.6.2 Formatter locking [format.formatter.locking]

[ð](#lib:enable_nonlocking_formatter_optimization)

`template<class T>
  constexpr bool enable_nonlocking_formatter_optimization = false;
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L7086)

*Remarks*: Pursuant to [[namespace.std]](namespace.std "16.4.5.2.1 Namespace std"),
users may specialize enable_nonlocking_formatter_optimization for
cv-unqualified program-defined types[.](#1.sentence-1)

Such specializations shall be usable in constant expressions ([[expr.const]](expr.const "7.7 Constant expressions"))
and have type const bool[.](#1.sentence-2)
