| <html lang="en"> |
| <head> |
| <title>What you can and what you cannot do in +load - Using the GNU Compiler Collection (GCC)</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="Using the GNU Compiler Collection (GCC)"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Executing-code-before-main.html#Executing-code-before-main" title="Executing code before main"> |
| <link rel="prev" href="Executing-code-before-main.html#Executing-code-before-main" title="Executing code before main"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, |
| 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, |
| 2008 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 1.2 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.--> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="What-you-can-and-what-you-cannot-do-in-+load"></a> |
| <a name="What-you-can-and-what-you-cannot-do-in-_002bload"></a> |
| <p> |
| Previous: <a rel="previous" accesskey="p" href="Executing-code-before-main.html#Executing-code-before-main">Executing code before main</a>, |
| Up: <a rel="up" accesskey="u" href="Executing-code-before-main.html#Executing-code-before-main">Executing code before main</a> |
| <hr> |
| </div> |
| |
| <h4 class="subsection">8.1.1 What you can and what you cannot do in <code>+load</code></h4> |
| |
| <p>The <code>+load</code> implementation in the GNU runtime guarantees you the following |
| things: |
| |
| <ul> |
| <li>you can write whatever C code you like; |
| |
| <li>you can send messages to Objective-C constant strings (<code>@"this is a |
| constant string"</code>); |
| |
| <li>you can allocate and send messages to objects whose class is implemented |
| in the same file; |
| |
| <li>the <code>+load</code> implementation of all super classes of a class are executed before the <code>+load</code> of that class is executed; |
| |
| <li>the <code>+load</code> implementation of a class is executed before the |
| <code>+load</code> implementation of any category. |
| |
| </ul> |
| |
| <p>In particular, the following things, even if they can work in a |
| particular case, are not guaranteed: |
| |
| <ul> |
| <li>allocation of or sending messages to arbitrary objects; |
| |
| <li>allocation of or sending messages to objects whose classes have a |
| category implemented in the same file; |
| |
| </ul> |
| |
| <p>You should make no assumptions about receiving <code>+load</code> in sibling |
| classes when you write <code>+load</code> of a class. The order in which |
| sibling classes receive <code>+load</code> is not guaranteed. |
| |
| <p>The order in which <code>+load</code> and <code>+initialize</code> are called could |
| be problematic if this matters. If you don't allocate objects inside |
| <code>+load</code>, it is guaranteed that <code>+load</code> is called before |
| <code>+initialize</code>. If you create an object inside <code>+load</code> the |
| <code>+initialize</code> method of object's class is invoked even if |
| <code>+load</code> was not invoked. Note if you explicitly call <code>+load</code> |
| on a class, <code>+initialize</code> will be called first. To avoid possible |
| problems try to implement only one of these methods. |
| |
| <p>The <code>+load</code> method is also invoked when a bundle is dynamically |
| loaded into your running program. This happens automatically without any |
| intervening operation from you. When you write bundles and you need to |
| write <code>+load</code> you can safely create and send messages to objects whose |
| classes already exist in the running program. The same restrictions as |
| above apply to classes defined in bundle. |
| |
| </body></html> |
| |