On 8 October 2010 14:18, Krzysztof Czainski <1czajnik@gmail.com> wrote:
Secondly, since this release, boost::construe_cast<std::string, tag::bin>(23) resulting in a std::string("10111") and visa versa. The user has the ability to add functionality here by implementing extra tags, by default tag::bin, tag::oct and tag::hex are implemented, with more to follow.
I use boost::lexical_cast for conversions from string. For conversions to string I rarely use boost::lexical_cast. Most of the time I need formated conversions, and I use boost::format:
lexical_cast<int>( "12" ) lexical_cast<string>( 12 ) str( format("0x%04x") % 12 )
When I need control over output format, I usually need more then just tag::hex, etc., and I like the printf/boost::format syntax for it. The alternative I dislike: ( ostringstream() << "0x" << hex << setw(4) << setfill('0') << 12 ).str()
Once I experienced having to fall back from boost::format to sprintf for efficiency reasons.
Conclusions: 1. For conversions from string I consider lexical_cast<T>( string ) sufficient, but I can imagine efficiency can be improved - if mesurements say so. 2. For unformated conversions to string: same as point 1.
I agree, that's the scope of this library. The tags are there as an extensibility point, and over time some common and convenient tags will be added, imagine a tag::no_case when you want to accept "True" or "TRUE" besides "true" for example.
3. For formated conversions to string: a more efficient boost::format would be something I would like to see (just a user's point of view, I have no idea how this could be implemented).
There already is a library in boost capable of this, boost.spirit's Karma, which construe_cast is partly build upon. It's not as trivial to use as boost.format but considerable faster, and I can highly recommend it. Please see http://www.boost.org/doc/libs/1_44_0/libs/spirit/doc/html/index.html for documentation.
Regards Kris
Regards, Jeroen