From: Ryan McConnehey Neal Becker wrote:

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How about constrained_value?

Is that a library or is it part of a bigger library? I can't find it in the 1.39 documentation.

Hi Ryan, You'll find simple constrained_value class in the DateTime library. More advanced implementation has been reviewed as a separate library and probably will be added to Boost in the future. I attach some details of this library below. Best regards, Robert

Here's the library synopsis:

The Boost Constrained Value library contains class templates useful for creating constrained objects. A simple example is an object representing an hour of a day, for which only integers from the range [0, 23] are valid values.

bounded_int<int, 0, 23>::type hour; hour = 20; // OK hour = 26; // exception!

Behavior in case of assignment of an invalid value can be customized. The library has a policy-based design to allow for flexibility in defining constraints and behavior in case of assignment of invalid values. Policies may be configured at compile-time for maximum efficiency or may be changeable at runtime if such dynamic functionality is needed.

The library can be downloaded from the here: http://rk.go.pl/f/constrained_value.zip

The documentation is also available online here: http://rk.go.pl/r/constrained_value