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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"><title>GAsyncResult</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2"><link rel="start" href="index.html" title="GIO Reference Manual"><link rel="up" href="async.html" title="Asynchronous I/O"><link rel="prev" href="GCancellable.html" title="GCancellable"><link rel="next" href="gio-GIOScheduler.html" title="GIOScheduler"><meta name="generator" content="GTK-Doc V1.9 (XML mode)"><link rel="stylesheet" href="style.css" type="text/css"><link rel="part" href="pt01.html" title="Part I. GIO Overview"><link rel="chapter" href="ch01.html" title="Introduction"><link rel="chapter" href="ch02.html" title="Compiling GIO applications"><link rel="chapter" href="ch03.html" title="Running GIO applications"><link rel="chapter" href="gio-extension-points.html" title="Extending GIO"><link rel="part" href="pt02.html" title="Part II. API Reference"><link rel="chapter" href="file_ops.html" title="File Operations"><link rel="chapter" href="file_mon.html" title="File System Monitoring"><link rel="chapter" href="async.html" title="Asynchronous I/O"><link rel="chapter" href="streaming.html" title="Streaming I/O"><link rel="chapter" href="types.html" title="File types and applications"><link rel="chapter" href="volume_mon.html" title="Volumes and Drives"><link rel="chapter" href="icons.html" title="Icons"><link rel="chapter" href="utils.html" title="Utilities"><link rel="chapter" href="extending.html" title="Extending GIO"><link rel="part" href="migrating.html" title="Part III. Migrating to GIO"><link rel="chapter" href="ch14.html" title="Migrating from POSIX to GIO"><link rel="chapter" href="ch15.html" title="Migrating from GnomeVFS to GIO"><link rel="chapter" href="gio-hierarchy.html" title="Object Hierarchy"><link rel="index" href="ix01.html" title="Index"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="2"><tr valign="middle"><td><a accesskey="p" href="GCancellable.html"><img src="left.png" width="24" height="24" border="0" alt="Prev"></a></td><td><a accesskey="u" href="async.html"><img src="up.png" width="24" height="24" border="0" alt="Up"></a></td><td><a accesskey="h" href="index.html"><img src="home.png" width="24" height="24" border="0" alt="Home"></a></td><th width="100%" align="center">GIO Reference Manual</th><td><a accesskey="n" href="gio-GIOScheduler.html"><img src="right.png" width="24" height="24" border="0" alt="Next"></a></td></tr><tr><td colspan="5" class="shortcuts"><nobr><a href="#id3059556" class="shortcut">Top</a>  |  <a href="#id3104150" class="shortcut">Description</a>  |  <a href="#id3104083" class="shortcut">Object Hierarchy</a>  |  <a href="#id3104106" class="shortcut">Prerequisites</a>  |  <a href="#id3104128" class="shortcut">Known Implementations</a></nobr></td></tr></table><div class="refentry" lang="en"><a name="GAsyncResult"></a><div class="titlepage"></div><div class="refnamediv"><table width="100%"><tr><td valign="top"><h2><a name="id3059556"></a><span class="refentrytitle">GAsyncResult</span></h2><p>GAsyncResult — Asynchronous Function Results</p></td><td valign="top" align="right"></td></tr></table></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">#include <gio/gio.h> <a class="link" href="GAsyncResult.html#GAsyncResult-struct">GAsyncResult</a>; <a class="link" href="GAsyncResult.html#GAsyncResultIface">GAsyncResultIface</a>;void (<a class="link" href="GAsyncResult.html#GAsyncReadyCallback">*GAsyncReadyCallback</a>) (<ahref="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GObject">GObject</a> *source_object, <a class="link" href="GAsyncResult.html" title="GAsyncResult">GAsyncResult</a> *res, <ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gpointer">gpointer</a> user_data);<ahref="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gpointer">gpointer</a> <a class="link" href="GAsyncResult.html#g-async-result-get-user-data">g_async_result_get_user_data</a> (<a class="link" href="GAsyncResult.html" title="GAsyncResult">GAsyncResult</a> *res);<ahref="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GObject">GObject</a>* <a class="link" href="GAsyncResult.html#g-async-result-get-source-object">g_async_result_get_source_object</a> (<a class="link" href="GAsyncResult.html" title="GAsyncResult">GAsyncResult</a> *res);</pre></div><div class="refsect1" lang="en"><a name="id3104083"></a><h2>Object Hierarchy</h2><pre class="synopsis"> GInterface +----GAsyncResult</pre></div><div class="refsect1" lang="en"><a name="id3104106"></a><h2>Prerequisites</h2><p>GAsyncResult requires <ahref="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GObject">GObject</a>.</p></div><div class="refsect1" lang="en"><a name="id3104128"></a><h2>Known Implementations</h2><p>GAsyncResult is implemented by <a class="link" href="GSimpleAsyncResult.html" title="GSimpleAsyncResult">GSimpleAsyncResult</a>.</p></div><div class="refsect1" lang="en"><a name="id3104150"></a><h2>Description</h2><p>Provides a base class for implementing asynchronous function results.</p><p>Asynchronous operations are broken up into two separate operationswhich are chained together by a <a class="link" href="GAsyncResult.html#GAsyncReadyCallback"><span class="type">GAsyncReadyCallback</span></a>. To beginan asynchronous operation, provide a <a class="link" href="GAsyncResult.html#GAsyncReadyCallback"><span class="type">GAsyncReadyCallback</span></a> to the asynchronous function. This callback will be triggered when the operation has completed, and will be passed a <a class="link" href="GAsyncResult.html" title="GAsyncResult"><span class="type">GAsyncResult</span></a> instance filled with the details of the operation's success or failure, the object the asynchronous function was started for and any error codes returned. The asynchronous callback function is then expected to call the corresponding "<code class="function">_finish()</code>" function with the object the function was called for, and the <a class="link" href="GAsyncResult.html" title="GAsyncResult"><span class="type">GAsyncResult</span></a> instance, and optionally, an <em class="parameter"><code>error</code></em> to grab any error conditions that may have occurred.</p><p>The purpose of the "<code class="function">_finish()</code>" function is to take the generic result of type <a class="link" href="GAsyncResult.html" title="GAsyncResult"><span class="type">GAsyncResult</span></a> and return the specific resultthat the operation in question yields (e.g. a <a class="link" href="GFileEnumerator.html" title="GFileEnumerator"><span class="type">GFileEnumerator</span></a> fora "enumerate children" operation). If the result or error statusof the operation is not needed, there is no need to call the"<code class="function">_finish()</code>" function, GIO will take care of cleaning up theresult and error information after the <a class="link" href="GAsyncResult.html#GAsyncReadyCallback"><span class="type">GAsyncReadyCallback</span></a> returns. It is also allowed to take a reference to the <a class="link" href="GAsyncResult.html" title="GAsyncResult"><span class="type">GAsyncResult</span></a> andcall "<code class="function">_finish()</code>" later.</p><p>Example of a typical asynchronous operation flow:</p><div class="informalexample"><pre class="programlisting">void _theoretical_frobnitz_async (Theoretical *t, GCancellable *c, GAsyncReadyCallback *cb, gpointer u);gboolean _theoretical_frobnitz_finish (Theoretical *t, GAsyncResult *res, GError **e);static void frobnitz_result_func (GObject *source_object, GAsyncResult *res, gpointer user_data){ gboolean success = FALSE; success = _theoretical_frobnitz_finish (source_object, res, NULL); if (success) g_printf ("Hurray!\n"); else g_printf ("Uh oh!\n"); /* ... */}int main (int argc, void *argv[]){ /* ... */ _theoretical_frobnitz_async (theoretical_data, NULL, frobnitz_result_func, NULL); /* ... */}</pre></div>⌨️ 快捷键说明
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