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authorJamie Lenehan <lenehan@twibble.org>2007-06-08 07:10:19 +0000
committerJamie Lenehan <lenehan@twibble.org>2007-06-08 07:10:19 +0000
commit483dff1bc453224980751aa6c1751e3225669d4d (patch)
tree258edb49d88f2f2f9681273f58845c5ea4a2fb65
parent376c9a6993298571a7049d2203232830c9cd1f87 (diff)
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usermanual/recipes: Put some basic info in the classes section.
-rw-r--r--usermanual/chapters/recipes.xml66
1 files changed, 62 insertions, 4 deletions
diff --git a/usermanual/chapters/recipes.xml b/usermanual/chapters/recipes.xml
index 5672067af8..18238cead0 100644
--- a/usermanual/chapters/recipes.xml
+++ b/usermanual/chapters/recipes.xml
@@ -2370,21 +2370,79 @@ addtask unpack_extra after do_unpack before do_patch</screen></para>
<section id="recipes_classes" xreflabel="classes">
<title>Classes: The separation of common functionality</title>
- <para>This section is to be completed.</para>
+ <para>Often a certain pattern is followed in more than one recipe, or
+ maybe some complex python based functionality is required to achieve the
+ desired end result. This is achieved through the use of classes, which can
+ be found in the classes subdirectory at the top-level of on OE
+ checkout.</para>
+
+ <para>Being aware of the available classes and understanding their
+ functionality is important because classes:</para>
<itemizedlist>
<listitem>
- <para>What are classes</para>
+ <para>Save developers time being performing actions that they would
+ otherwise need to perform themselves;</para>
</listitem>
<listitem>
- <para>How you use classes</para>
+ <para>Perform a lot of actions in the background making a lot of
+ recipes difficult to understand unless you are aware of classes and
+ how they work;</para>
</listitem>
<listitem>
- <para>Some example - autotools, update-r.d, distutils</para>
+ <para>A lot of detail on how things work can be learnt for looking at
+ how classes are implement.</para>
</listitem>
</itemizedlist>
+
+ <para>A class is used via the inherit method. The following is an example
+ for the <emphasis>curl</emphasis> recipe showing that it uses three
+ classes:<screen>inherit autotools pkgconfig binconfig</screen>In this case
+ it is utilising the services of three separate classes:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>autotools</term>
+
+ <listitem>
+ <para>The <xref linkend="autotools_class" /> is used by programs
+ that use the GNU configuration tools and takes care of the
+ configuration and compilation of the software;</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>pkgconfig</term>
+
+ <listitem>
+ <para>The <xref linkend="pkgconfig_class" /> is used to stage the
+ <emphasis>.pc</emphasis> files which are used by the <emphasis
+ role="bold">pkg-config</emphasis> program to provide information
+ about the package to other software that wants to link to this
+ software;</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>binconfig</term>
+
+ <listitem>
+ <para>The <xref linkend="binconfig_class" /> is used to stage the
+ <emphasis>&lt;name&gt;-config</emphasis> files which are used to
+ provide information about the package to other software that wants
+ to link to this software;</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Each class is implemented via the file in the <emphasis
+ role="bold">classes</emphasis> subdirectory named <emphasis
+ role="bold">&lt;classname&gt;.bbclass</emphasis> and these can be examined
+ for further details on a particular class, although sometimes it's not
+ easy to understand everything that's happening. Many of the classes are
+ covered in detail in various sections in this user manual.</para>
</section>
<section id="recipes_staging" xreflabel="staging">