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[ceph.git] / ceph / src / boost / libs / phoenix / doc / starter_kit / arguments.qbk

[/==============================================================================
    Copyright (C) 2001-2010 Joel de Guzman
    Copyright (C) 2001-2005 Dan Marsden
    Copyright (C) 2001-2010 Thomas Heller

    Distributed under the Boost Software License, Version 1.0. (See accompanying
    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
===============================================================================/]

[section Arguments]

Arguments are also functions? You bet!

Until now, we have been dealing with expressions returning a nullary function.
Arguments, on the other hand, evaluate to an N-ary function. An argument
represents the Nth argument. There are a few predefined arguments arg1,
arg2, arg3, arg4 and so on (and it's __bll__ counterparts: _1, _2, _3, _4 and so
on). Examples:

    arg1 // one-or-more argument function that returns its first argument
    arg2 // two-or-more argument function that returns its second argument
    arg3 // three-or-more argument function that returns its third argument

`argN` returns the Nth argument. Examples:

    int i = 3;
    char const* s = "Hello World";
    std::cout << arg1(i) << std::endl;        // prints 3
    std::cout << arg2(i, s) << std::endl;     // prints "Hello World"

(See [@../../example/arguments.cpp arguments.cpp])

[blurb __tip__ Learn more about arguments [link phoenix.modules.core.arguments here.]]

[endsect]