Note: This paper explores potential future standardization directions and alternatives. It does not discuss or propose to amend the C++14 Committee Draft paper whose ballot is currently in progress.

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Document number: N3699

Date: 2013-05-27

A proposal to add a generalized callable negator

by Tomasz Kamiński

Excerpt:

The standard negators not1 and not2 accept only unary and binary functors that define argument_type or first_argument_type and second_argument_type respectively, which make them unusable with results of standard library functions such as bind and mem_fn. Furthermore, with relation to N3421, they cannot be used with new operator functor specializations.

This proposal addresses the problem by introducing a template function not_fn that returns complement of arbitrary predicate.