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Boost Numeric Conversion Library |
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The Boost Numeric Conversion library is a collection of tools to describe and perform conversions between values of different numeric types.
The library includes a special alternative for a subset of std::numeric_limits<>,
the bounds<> traits class, which provides
a consistent way to obtain the boundary values for the
range of a numeric type.
It also includes a set of trait classes which describes the compile-time properties of a conversion from a source to a target numeric type. Both arithmetic and user-defined numeric types can be used.
A policy-based converter object which uses conversion_traits
to select an optimized implementation is supplied.
Such implementation uses an optimal range checking code suitable for the source/target combination.
The converter's out-of-range behavior can be customized via an OverflowHandler
policy.
For floating-point to integral conversions, the rounding mode can be selected via
the Float2IntRounder policy.
A custom low-level conversion routine (for UDTs for instance) can be passed
via a RawConverter policy.
The optimized automatic range-checking logic can be overridden via a UserRangeChecker
policy.
Pre-formal review:
Kevlin Henney, with help from David Abrahams and Beman Dawes, originally contributed the previous version of numeric_cast<> which already presented the idea of a runtime range check.
Later, Eric Ford, Kevin Lynch and the author spotted some genericity problems with that numeric_cast<> which prevented it from being used in a generic layer of math functions.
An improved numeric_cast<> which properly handled all combinations of arithmetic types was presented.
David Abrahams and Beman Dawes acknowledged the need of an improved version of numeric_cast<> and supported the submission as originally laid out. Daryl Walker and Darin Adler made some important comments and proposed fixes to the original submission.Special thanks go to Bj�rn Karlsoon who helped the author considerably. Having found the problems with numeric_cast<> himself, he revised very carefully the original submission and spot a subtle bug in the range checking implementation. He also wrote part of this documentation and proof-read and corrected other parts. And most importantly: the features now presented here in this library evolved from the original submission as a result of the useful private communications between Bj�rn and the author.
Post-formal review:
Guillaume Melquiond spoted some documentation and code issues, particularly about rounding conversions.
The following people contributed an important review of the design, documentation and code: Kevin Lynch, Thorsten Ottosen, Paul Bristow,
Daryle Walker, Jhon Torjo, Eric Ford, Gennadiy Rozental.
Revised 23 June 2004
� Copyright Fernando Luis Cacciola Carballal, 2004
Use, modification, and distribution are subject to the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at www.boost.org/LICENSE_1_0.txt)
