John Salmon <john <at> thesalmons.org> writes:
Yes. It's possible to write more "defensive" inserters and extractors. That's beside the point. The patch allows lexical_cast to work with Udts whose implementations are not so careful. It does so while passing all existing regressions (except for two which are modified to return a very reasonable result rather than throwing a somewhat surprising exception).
I don't have an access to my home system to check if your patch doesn't break this: BOOST_CHECK_EQUAL(" a b c " == lexical_cast<std::string>(" a b c ")); Does it?
Nothing in lexical_cast's documentation even hints that one should beware of whitespace when reading and writing from streams. There is no reason for lexical_cast to insist on this degree of care and attention to detail in the implementations of user-defined types. The naive pair of operator<< and operator>> in the original post work perfectly well when operating on iostreams in their standard, default state. They work perfectly well for the user who never heard of lexical_cast who uses the standard istringstream idiom:
istringstream iss("13 19"); Udt Foo; iss >> Foo; assert( Foo == Udt(13, 19) );
Shouldn't lexical_cast do just as well? When I see something like the above in a colleague's code, and I suggest lexical_cast, should I really have to also warn him about carefully handling whitespace in the Udt extractor?
I'll think about it. But noskipws is there for a good reason. You can search the boost archive. -- Alexander Nasonov