[ceph.git] / ceph / src / boost / libs / convert / doc / rationale.qbk

[/
  Copyright (c) Vladimir Batov 2009-2016
  Distributed under the Boost Software License, Version 1.0.
  See copy at http://www.boost.org/LICENSE_1_0.txt.
]

[section Rationale]

I was using textual configuration files extensively and also was processing and preparing considerable amounts of data in XML. Consequently, I had a need for an ['extendible] library that would provide a ['uniform] interface to convert various data between their internal binary representations and external (predominantly textual) representations. 

The `boost::lexical_cast` library (with its orthogonal and extendible design) looked very promising compared to others (see [@http://www.gotw.ca/publications/mill19.htm The String Formatters of Manor Farm] by H. Sutter for the discussion of alternatives). Unfortunately, 

* many deployed user types simply did not meet `boost::lexical_cast` requirements (namely, [@http://en.cppreference.com/w/cpp/concept/DefaultConstructible ['Default Constructibility]]); 
* failure to convert a user-provided configuration parameter was not that rare or exceptional to justify the hassle and the overhead of exception processing and, consequently, additional flexibility (['if], ['when] and ['how]) to handle conversion failures was needed;
* additional conversion-related functionality (such as formatting and locale support) were needed. 

The original hope was to see `boost::lexical_cast` extended to be applicable to a wider range of deployment scenarios. However, after discussions with Kevlin Henney (the `boost::lexical_cast` author) and in the Boost Developers forum it was collectively decided that the desired extensions were not compatible with the original design and the idea of what `boost::lexical_cast` embodied and, therefore, a new component with richer interface and functionality was needed. That decision resulted in the development of ['Boost.Convert] described in this document.

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Commit	Line	Data
7c673cae FG	1	[/
	2	Copyright (c) Vladimir Batov 2009-2016
	3	Distributed under the Boost Software License, Version 1.0.
	4	See copy at http://www.boost.org/LICENSE_1_0.txt.
	5	]
	6
	7	[section Rationale]
	8
	9	I was using textual configuration files extensively and also was processing and preparing considerable amounts of data in XML. Consequently, I had a need for an ['extendible] library that would provide a ['uniform] interface to convert various data between their internal binary representations and external (predominantly textual) representations.
	10
	11	The `boost::lexical_cast` library (with its orthogonal and extendible design) looked very promising compared to others (see [@http://www.gotw.ca/publications/mill19.htm The String Formatters of Manor Farm] by H. Sutter for the discussion of alternatives). Unfortunately,
	12
	13	* many deployed user types simply did not meet `boost::lexical_cast` requirements (namely, [@http://en.cppreference.com/w/cpp/concept/DefaultConstructible ['Default Constructibility]]);
	14	* failure to convert a user-provided configuration parameter was not that rare or exceptional to justify the hassle and the overhead of exception processing and, consequently, additional flexibility (['if], ['when] and ['how]) to handle conversion failures was needed;
	15	* additional conversion-related functionality (such as formatting and locale support) were needed.
	16
	17	The original hope was to see `boost::lexical_cast` extended to be applicable to a wider range of deployment scenarios. However, after discussions with Kevlin Henney (the `boost::lexical_cast` author) and in the Boost Developers forum it was collectively decided that the desired extensions were not compatible with the original design and the idea of what `boost::lexical_cast` embodied and, therefore, a new component with richer interface and functionality was needed. That decision resulted in the development of ['Boost.Convert] described in this document.
	18
	19	[endsect]