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### 1057. `RandomNumberEngineAdaptor`

Section: 28.5 [rand] Status: NAD Concepts Submitter: Alisdair Meredith Opened: 2009-03-12 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

The `RandomNumberEngineAdaptor` concept breaks precedent in the way the library has been specified by grouping requirements into a concept that is never actually used in the library.

This is undoubtedly a very helpful device for documentation, but we are not comfortable with the precedent - especially as we have rejected national body comments on the same grounds.

Suggest either removing the concept, or providing an algorithm/type that requires this concept in their definition (such as a factory function to create new engines).

The preference is to create a single new algorithm and retain the value of the existing documentation.

[ Batavia (2009-05): ]

> Walter points out that it is unlikely that any algorithm would ever require this concept, but that the concept nonetheless is useful as documentation, and (via concept maps) as a means of checking specific adapters.

> Alisdair disagrees as to the concept's value as documentation.

> Marc points out that the `RandomNumberDistribution` is also a concept not used elsewhere in the Standard.

> Pete agrees that a policy of not inventing concepts that aren't used in the Standard is a good starting point, but should not be used as a criterion for rejecting a concept.

> Move to Open.

Proposed resolution: