Читаем Thinking In C++. Volume 2: Practical Programming полностью

^[27] Thanks to Reg Charney of the C++ Standards Committee for suggesting this trick.

^[28] Some of the material in this chapter was originally created by Nancy Nicolaisen.

^[29] It’s difficult to make reference-counting implementations thread safe. (See Herb Sutter, More Exceptional C++, pp. 104–14). See Chapter 10 for more on programming with multiple threads.

^[30] It as an abbreviation for "no position."

^[31] Discussed in depth in Chapter 6.

^[32] To keep the exposition simple, this version does not handle nested tags, such as comments.

^[33] It is tempting to use mathematics here to factor out some of these calls to erase( ), but since in some cases one of the operands is string::npos (the largest unsigned integer available), integer overflow occurs and wrecks the algorithm.

^[34] Alert: For the safety reasons mentioned, the C++ Standards Committee is considering a proposal to redefine string::operator[] to behave identically to string::at() for C++0x.

^[35] Your implementation can define all three template arguments here. Because the last two template parameters have default arguments, such a declaration is equivalent to what we show here.

^[36] Beware that some versions of Microsoft Word erroneously replace single quote characters with an extended ASCII character when you save a document as text, which of course causes a compile error. We have no idea why this happens. Just replace the character manually with an apostrophe.

^[37] POSIX, an IEEE standard, stands for "Portable Operating System Interface" and is a generalization of many of the low-level system calls found in UNIX systems.

^[38] The implementation and test files for FULLWRAP are available in the freely distributed source code for this book. See the preface for details.

^[39] Explained in depth in Chapter 5.

^[40] For this reason, we can write ios::failbit instead of ios_base::failbit to save typing.

^[41] It is customary to use operator void*( ) in preference to operator bool( ) because the implicit conversions from bool to int may cause surprises, should you errantly place a stream in a context where an integer conversion can be applied. The operator void*( ) function will only implicitly be called in the body of a Boolean expression.

^[42] An integral type used to hold single-bit flags.

^[43] A more in-depth treatment of stream buffers and streams in general can be found in Langer & Kreft’s, Standard C++ IOStreams and Locales, Addison-Wesley, 1999.

^[44] For more information on machine epsilon and floating-point computation in general, see Chuck’s article, "The Standard C Library, Part 3", C/C++ Users Journal, March 1995, also available at www.freshsources.com/1995006a.htm.

^[45] Before putting nl into a header file, make it an inline function (see Chapter 7).

^[46] Jerry Schwarz is the designer of iostreams.

^[47] See the Langer & Kreft book mentioned earlier for more detailed information.

^[48] See, for example, Dinkumware’s Abridged library at www.dinkumware.com. This library omits locale support. and exception support is optional.

^[49] Vandevoorde and Josuttis, C++ Templates: The Complete Guide, Addison-Wesley, 2003.

^[50] The C++ standards committee is considering relaxing the only-within-a-template rule for these disambiguation hints, and some compilers are allowing then in non-template code already.

^[51] See Stroustrup, The C++ Programming Language, 3^rd Edition, Addison-Wesley, pp. 335-336.

^[52] Technically, comparing two pointers not inside the same array is undefined behavior, but compilers nowadays don’t complain about this. All the more reason to do it right.

^[53] We are indebted to Nathan Myers for this example.

^[54] Such as type information encoded in a decorated name.

^[55] C++ compilers can introduce names anywhere they want, however. Fortunately, most don’t declare names they don’t need.

^[56] If you’re interested in seeing the proposal, it’s Core Issue 352.

^[57] A reference to the British animated short feature The Wrong Trousers by Nick Park.

^[58] We discuss vector in depth in Chapter 7.

^[59] Since the forwarding functions are inline, no code is generated at all!

^[60] Also called Koenig lookup, after Andrew Koenig, who first proposed the technique to the C++ standards committee. ADL applies universally, whether templates are involved or not.

^[61] In a talk given at The C++ Seminar, Portland, OR, September, 2001.

^[62] Another template idiom, mixin inheritance, is covered in Chapter 9.