std::is_placeholder

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Defined in header <functional>

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template< class T >
struct is_placeholder;

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If T is the type of a standard placeholder (_1, _2, _3, ...), then this template is derived from Template:cpp, Template:cpp, Template:cpp, respectively. If T is not a standard placeholder type, this template is derived from Template:cpp.

The template may be specialized for any user-defined type which should be treated by Template:cpp as if it was a placeholder for unbound arguments.

Inherited from std::integral_constant

Member constants

value [static]

placeholder value or 0 for non-placeholder types (public static member constant)

Member functions

operator int	converts the object to int, returns value (public member function)
operator() (C++14)	returns value (public member function)

Member types

Type	Definition
value_type	int
type	std::integral_constant<int, value>

See also

bind (C++11)	binds one or more arguments to a function object (function template)
_1, _2, _3, _4, ... (C++11)	placeholders for the unbound arguments in a std::bind expression (constant)