1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Chapter 1. Boost.Convert 2.0</title> 5<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="index.html" title="Chapter 1. Boost.Convert 2.0"> 8<link rel="next" href="boost_convert/introduction.html" title="Introduction"> 9</head> 10<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 11<table cellpadding="2" width="100%"><tr> 12<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> 13<td align="center"><a href="../../../../index.html">Home</a></td> 14<td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> 15<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 16<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 17<td align="center"><a href="../../../../more/index.htm">More</a></td> 18</tr></table> 19<hr> 20<div class="spirit-nav"><a accesskey="n" href="boost_convert/introduction.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a></div> 21<div class="chapter"> 22<div class="titlepage"><div> 23<div><h2 class="title"> 24<a name="convert"></a>Chapter 1. Boost.Convert 2.0</h2></div> 25<div><div class="author"><h3 class="author"> 26<span class="firstname">Vladimir</span> <span class="surname">Batov</span> 27</h3></div></div> 28<div><p class="copyright">Copyright © 2009-2016 Vladimir Batov</p></div> 29<div><div class="legalnotice"> 30<a name="convert.legal"></a><p> 31 Distributed under the Boost Software License, Version 1.0. See copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>. 32 </p> 33</div></div> 34</div></div> 35<div class="toc"> 36<p><b>Table of Contents</b></p> 37<dl class="toc"> 38<dt><span class="section"><a href="index.html#boost_convert.rationale">Rationale</a></span></dt> 39<dt><span class="section"><a href="boost_convert/introduction.html">Introduction</a></span></dt> 40<dt><span class="section"><a href="boost_convert/getting_started.html">Getting Started</a></span></dt> 41<dd><dl> 42<dt><span class="section"><a href="boost_convert/getting_started.html#boost_convert.getting_started.basic_deployment">Basic 43 Deployment</a></span></dt> 44<dt><span class="section"><a href="boost_convert/getting_started/flexibility_and_adaptability_to_change.html">Flexibility 45 and Adaptability to Change</a></span></dt> 46<dt><span class="section"><a href="boost_convert/getting_started/basic_conversion_failure_detection.html">Basic 47 Conversion-Failure Detection</a></span></dt> 48</dl></dd> 49<dt><span class="section"><a href="boost_convert/error_detection.html">Better Error Detection</a></span></dt> 50<dt><span class="section"><a href="boost_convert/default_converter.html">Default Converter</a></span></dt> 51<dt><span class="section"><a href="boost_convert/alternative_interface.html">Alternative Interface</a></span></dt> 52<dt><span class="section"><a href="boost_convert/converters.html">Converters</a></span></dt> 53<dt><span class="section"><a href="boost_convert/integration_of_user_types.html">Integration of 54 User-Defined Types</a></span></dt> 55<dt><span class="section"><a href="boost_convert/algorithms.html">Boost.Convert with Standard Algorithms</a></span></dt> 56<dt><span class="section"><a href="boost_convert/performance.html">Performance</a></span></dt> 57<dd><dl> 58<dt><span class="section"><a href="boost_convert/performance.html#boost_convert.performance.converters_compared">Converters 59 Compared</a></span></dt> 60<dt><span class="section"><a href="boost_convert/performance/boost_convert_overhead.html">Boost.Convert 61 Overhead</a></span></dt> 62<dt><span class="section"><a href="boost_convert/performance/the_bigger_picture.html">The Bigger 63 Picture</a></span></dt> 64</dl></dd> 65<dt><span class="section"><a href="boost_convert/other_conversions.html">Beyond Basic Conversions</a></span></dt> 66<dt><span class="section"><a href="boost_convert/converters_detail.html">Converters in Detail</a></span></dt> 67<dd><dl> 68<dt><span class="section"><a href="boost_convert/converters_detail.html#boost_convert.converters_detail.lexical_cast_converter"><span class="emphasis"><em>boost::cnv::lexical_cast</em></span> 69 Converter</a></span></dt> 70<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter.html"><span class="emphasis"><em>boost::cnv::stream</em></span> 71 Converter</a></span></dt> 72<dd><dl> 73<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter.html#boost_convert.converters_detail.stream_converter.formatting_support">Formatting 74 Support</a></span></dt> 75<dd><dl> 76<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter.html#boost_convert.converters_detail.stream_converter.formatting_support.numeric_base">Numeric 77 Base</a></span></dt> 78<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter.html#boost_convert.converters_detail.stream_converter.formatting_support.field_width__fill_character_and_adjustment">Field 79 Width, Fill Character and Adjustment</a></span></dt> 80<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter.html#boost_convert.converters_detail.stream_converter.formatting_support.leading_whitespace_characters">Leading 81 Whitespace Characters</a></span></dt> 82<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter.html#boost_convert.converters_detail.stream_converter.formatting_support.format_of_boolean_values">Format 83 of Boolean Values</a></span></dt> 84</dl></dd> 85<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter/locale_support.html">Locale 86 Support</a></span></dt> 87<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter/supported_string_types.html">Supported 88 String Types</a></span></dt> 89<dd><dl> 90<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter/supported_string_types.html#boost_convert.converters_detail.stream_converter.supported_string_types.wide_string">Wide 91 String</a></span></dt> 92<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter/supported_string_types/custom_string_types.html">Custom 93 String Types</a></span></dt> 94</dl></dd> 95<dt><span class="section"><a href="boost_convert/converters_detail/stream_converter/the___default_constructible__type_requirement.html">The 96 <span class="emphasis"><em>Default Constructible</em></span> Type Requirement</a></span></dt> 97</dl></dd> 98<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter.html"><span class="emphasis"><em>boost::cnv::strtol</em></span> 99 Converter</a></span></dt> 100<dd><dl> 101<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter.html#boost_convert.converters_detail.strtol_converter.basic_deployment">Basic 102 Deployment</a></span></dt> 103<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter/formatting_support.html">Formatting 104 Support</a></span></dt> 105<dd><dl> 106<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter/formatting_support.html#boost_convert.converters_detail.strtol_converter.formatting_support.numeric_base__bin__oct__dec__hex_">Numeric 107 Base (bin, oct, dec, hex)</a></span></dt> 108<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter/formatting_support/field_width__fill_character_and_adjustment.html">Field 109 Width, Fill Character and Adjustment</a></span></dt> 110<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter/formatting_support/leading_whitespace_characters.html">Leading 111 Whitespace Characters</a></span></dt> 112<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter/formatting_support/floating_point_precision.html">Floating-Point 113 Precision</a></span></dt> 114</dl></dd> 115<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter/supported_string_types.html">Supported 116 String Types</a></span></dt> 117<dd><dl> 118<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter/supported_string_types.html#boost_convert.converters_detail.strtol_converter.supported_string_types.wide_string">Wide 119 String</a></span></dt> 120<dt><span class="section"><a href="boost_convert/converters_detail/strtol_converter/supported_string_types/custom_string_types.html">Custom 121 String Types</a></span></dt> 122</dl></dd> 123</dl></dd> 124</dl></dd> 125<dt><span class="section"><a href="boost_convert/design_notes.html">Design 126 Notes</a></span></dt> 127<dd><dl> 128<dt><span class="section"><a href="boost_convert/design_notes.html#boost_convert.design_notes.requirements">Requirements</a></span></dt> 129<dt><span class="section"><a href="boost_convert/design_notes/converter_signature.html">Converter 130 Signature</a></span></dt> 131<dt><span class="section"><a href="boost_convert/design_notes/user_interface_signature.html">User 132 Interface Signature</a></span></dt> 133</dl></dd> 134<dt><span class="section"><a href="boost_convert/supporting_tools.html">Supporting Tools</a></span></dt> 135<dd><dl> 136<dt><span class="section"><a href="boost_convert/supporting_tools.html#boost_convert.supporting_tools.boost__cnv__range">boost::cnv::range</a></span></dt> 137<dt><span class="section"><a href="boost_convert/supporting_tools/boost__cnv__is_range.html">boost::cnv::is_range</a></span></dt> 138<dt><span class="section"><a href="boost_convert/supporting_tools/boost_declare_has_member.html">BOOST_DECLARE_HAS_MEMBER</a></span></dt> 139<dt><span class="section"><a href="boost_convert/supporting_tools/boost_declare_is_callable.html">BOOST_DECLARE_IS_CALLABLE</a></span></dt> 140<dt><span class="section"><a href="boost_convert/supporting_tools/boost__cnv__is_cnv.html">boost::cnv::is_cnv</a></span></dt> 141</dl></dd> 142<dt><span class="section"><a href="boost_convert/supported_compilers.html">Supported Compilers</a></span></dt> 143<dt><span class="section"><a href="boost_convert/acknowledgements.html">Acknowledgements</a></span></dt> 144<dt><span class="section"><a href="boost_convert_c___reference.html">Boost.Convert C++ Reference</a></span></dt> 145<dd><dl> 146<dt><span class="section"><a href="boost_convert_c___reference.html#header.boost.convert_hpp">Header <boost/convert.hpp></a></span></dt> 147<dd><dl></dl></dd> 148<dt><span class="section"><a href="header/boost/convert/base_hpp.html">Header <boost/convert/base.hpp></a></span></dt> 149<dd><dl></dl></dd> 150<dt><span class="section"><a href="header/boost/convert/lexical_cast_hpp.html">Header <boost/convert/lexical_cast.hpp></a></span></dt> 151<dd><dl></dl></dd> 152<dt><span class="section"><a href="header/boost/convert/parameters_hpp.html">Header <boost/convert/parameters.hpp></a></span></dt> 153<dt><span class="section"><a href="header/boost/convert/printf_hpp.html">Header <boost/convert/printf.hpp></a></span></dt> 154<dd><dl></dl></dd> 155<dt><span class="section"><a href="header/boost/convert/spirit_hpp.html">Header <boost/convert/spirit.hpp></a></span></dt> 156<dd><dl></dl></dd> 157<dt><span class="section"><a href="header/boost/convert/stream_hpp.html">Header <boost/convert/stream.hpp></a></span></dt> 158<dd><dl></dl></dd> 159<dt><span class="section"><a href="header/boost/convert/strtol_hpp.html">Header <boost/convert/strtol.hpp></a></span></dt> 160<dd><dl></dl></dd> 161<dt><span class="section"><a href="header/boost/make_default_hpp.html">Header <boost/make_default.hpp></a></span></dt> 162<dd><dl></dl></dd> 163</dl></dd> 164<dt><span class="section"><a href="index/s18.html">Index</a></span></dt> 165</dl> 166</div> 167<div class="section"> 168<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 169<a name="boost_convert.rationale"></a><a class="link" href="index.html#boost_convert.rationale" title="Rationale">Rationale</a> 170</h2></div></div></div> 171<p> 172 I was using textual configuration files extensively and was also processing 173 and preparing considerable amounts of data in XML. Consequently, I had a need 174 for an <span class="emphasis"><em>extendible</em></span> library that would provide a <span class="emphasis"><em>uniform</em></span> 175 interface to convert various data between their internal binary representations 176 and external (predominantly textual) representations. 177 </p> 178<p> 179 The <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lexical_cast</span></code> library (with its orthogonal 180 and extendible design) looked very promising compared to others (see <a href="http://www.gotw.ca/publications/mill19.htm" target="_top">The String Formatters of Manor 181 Farm</a> by H. Sutter for the discussion of alternatives). Unfortunately, 182 </p> 183<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 184<li class="listitem"> 185 many deployed user types simply did not meet <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lexical_cast</span></code> 186 requirements (namely, <a href="http://en.cppreference.com/w/cpp/named_req/DefaultConstructible" target="_top"><span class="emphasis"><em>Default 187 Constructibility</em></span></a>); 188 </li> 189<li class="listitem"> 190 failure to convert a user-provided configuration parameter was not that 191 rare or exceptional to justify the hassle and the overhead of exception 192 processing; consequently, additional flexibility (<span class="emphasis"><em>if</em></span>, 193 <span class="emphasis"><em>when</em></span> and <span class="emphasis"><em>how</em></span>) in handling conversion 194 failures was needed; 195 </li> 196<li class="listitem"> 197 additional conversion-related functionality (such as formatting and locale 198 support) were needed. 199 </li> 200</ul></div> 201<p> 202 The original hope was to see <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lexical_cast</span></code> 203 extended to be applicable to a wider range of deployment scenarios. However, 204 after discussions with Kevlin Henney (the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lexical_cast</span></code> 205 author) and in the Boost Developers forum it was collectively decided that 206 the desired extensions were not compatible with the original design and the 207 idea of what <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lexical_cast</span></code> embodied and, therefore, a new 208 component with richer interface and functionality was needed. That decision 209 resulted in the development of <span class="emphasis"><em>Boost.Convert</em></span> described 210 in this document. 211 </p> 212</div> 213</div> 214<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 215<td align="left"><p><small>Last revised: August 11, 2020 at 15:01:23 GMT</small></p></td> 216<td align="right"><div class="copyright-footer"></div></td> 217</tr></table> 218<hr> 219<div class="spirit-nav"><a accesskey="n" href="boost_convert/introduction.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a></div> 220</body> 221</html> 222
