You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
132 lines
5.1 KiB
HTML
132 lines
5.1 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- Copyright (C) 1988-2018 Free Software Foundation, Inc.
|
|
|
|
Permission is granted to copy, distribute and/or modify this document
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
|
any later version published by the Free Software Foundation; with the
|
|
Invariant Sections being "Funding Free Software", the Front-Cover
|
|
Texts being (a) (see below), and with the Back-Cover Texts being (b)
|
|
(see below). A copy of the license is included in the section entitled
|
|
"GNU Free Documentation License".
|
|
|
|
(a) The FSF's Front-Cover Text is:
|
|
|
|
A GNU Manual
|
|
|
|
(b) The FSF's Back-Cover Text is:
|
|
|
|
You have freedom to copy and modify this GNU Manual, like GNU
|
|
software. Copies published by the Free Software Foundation raise
|
|
funds for GNU development. -->
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>C++ Concepts (Using the GNU Compiler Collection (GCC))</title>
|
|
|
|
<meta name="description" content="C++ Concepts (Using the GNU Compiler Collection (GCC))">
|
|
<meta name="keywords" content="C++ Concepts (Using the GNU Compiler Collection (GCC))">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content="makeinfo">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<link href="index.html#Top" rel="start" title="Top">
|
|
<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="C_002b_002b-Extensions.html#C_002b_002b-Extensions" rel="up" title="C++ Extensions">
|
|
<link href="Deprecated-Features.html#Deprecated-Features" rel="next" title="Deprecated Features">
|
|
<link href="Type-Traits.html#Type-Traits" rel="prev" title="Type Traits">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.indentedblock {margin-right: 0em}
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
|
blockquote.smallquotation {font-size: smaller}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
div.smalldisplay {margin-left: 3.2em}
|
|
div.smallexample {margin-left: 3.2em}
|
|
div.smalllisp {margin-left: 3.2em}
|
|
kbd {font-style: oblique}
|
|
pre.display {font-family: inherit}
|
|
pre.format {font-family: inherit}
|
|
pre.menu-comment {font-family: serif}
|
|
pre.menu-preformatted {font-family: serif}
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
|
pre.smallexample {font-size: smaller}
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
|
pre.smalllisp {font-size: smaller}
|
|
span.nolinebreak {white-space: nowrap}
|
|
span.roman {font-family: initial; font-weight: normal}
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en">
|
|
<a name="C_002b_002b-Concepts"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Deprecated-Features.html#Deprecated-Features" accesskey="n" rel="next">Deprecated Features</a>, Previous: <a href="Type-Traits.html#Type-Traits" accesskey="p" rel="prev">Type Traits</a>, Up: <a href="C_002b_002b-Extensions.html#C_002b_002b-Extensions" accesskey="u" rel="up">C++ Extensions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<a name="C_002b_002b-Concepts-1"></a>
|
|
<h3 class="section">7.10 C++ Concepts</h3>
|
|
|
|
<p>C++ concepts provide much-improved support for generic programming. In
|
|
particular, they allow the specification of constraints on template arguments.
|
|
The constraints are used to extend the usual overloading and partial
|
|
specialization capabilities of the language, allowing generic data structures
|
|
and algorithms to be “refined” based on their properties rather than their
|
|
type names.
|
|
</p>
|
|
<p>The following keywords are reserved for concepts.
|
|
</p>
|
|
<dl compact="compact">
|
|
<dt><code>assumes</code></dt>
|
|
<dd><p>States an expression as an assumption, and if possible, verifies that the
|
|
assumption is valid. For example, <code>assume(n > 0)</code>.
|
|
</p>
|
|
</dd>
|
|
<dt><code>axiom</code></dt>
|
|
<dd><p>Introduces an axiom definition. Axioms introduce requirements on values.
|
|
</p>
|
|
</dd>
|
|
<dt><code>forall</code></dt>
|
|
<dd><p>Introduces a universally quantified object in an axiom. For example,
|
|
<code>forall (int n) n + 0 == n</code>).
|
|
</p>
|
|
</dd>
|
|
<dt><code>concept</code></dt>
|
|
<dd><p>Introduces a concept definition. Concepts are sets of syntactic and semantic
|
|
requirements on types and their values.
|
|
</p>
|
|
</dd>
|
|
<dt><code>requires</code></dt>
|
|
<dd><p>Introduces constraints on template arguments or requirements for a member
|
|
function of a class template.
|
|
</p>
|
|
</dd>
|
|
</dl>
|
|
|
|
<p>The front end also exposes a number of internal mechanism that can be used
|
|
to simplify the writing of type traits. Note that some of these traits are
|
|
likely to be removed in the future.
|
|
</p>
|
|
<dl compact="compact">
|
|
<dt><code>__is_same (type1, type2)</code></dt>
|
|
<dd><p>A binary type trait: true whenever the type arguments are the same.
|
|
</p>
|
|
</dd>
|
|
</dl>
|
|
|
|
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|