boost/libs/convert/doc/other.qbk

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  Copyright (c) Vladimir Batov 2009-2020
  Distributed under the Boost Software License, Version 1.0.
  See copy at http://www.boost.org/LICENSE_1_0.txt.
]

[section:other_conversions Beyond Basic Conversions]

An interesting (and yet to be fully explored) property of the described design is that ['Boost.Convert] is not limited to string-to-type and type-to-string conversions. The `boost::convert()` interface is type-agnostic and the plugged-in converter ultimately dictates what type transformations are available. Consequently, a wide range of conversion\/transformation-related tasks can be addressed and ['deployed uniformly] by plugging-in special-purpose converters.

As an experiment, the code below (taken from ['test/encryption.cpp]) does not do type conversion. Instead, it applies a string transformation:

 string encrypted = boost::convert<string>("ABC", my_cypher).value();
 string decrypted = boost::convert<string>(encrypted, my_cypher).value();

 BOOST_ASSERT(encrypted == "123");
 BOOST_ASSERT(decrypted == "ABC");

The original "ABC" string is "encrypted" as "123" first and then "123" is "decrypted" back to its original "ABC" form.

Similarly, I personally do not immediately see as objectionable string-transformations like:

 std::u8string utf8 = boost::convert<std::u8string>(utf32_str, cnv);
 std::u8string utf8 = boost::convert<std::u8string>(mbcs_str, cnv);

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