Attachment 123501 Details for Bug 166855 – file.diff

[patch] file.diff

file.diff (text/plain), 2.07 KB, created by A.J. Kehoe IV on 2012-04-11 19:40:11 UTC

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Creator: A.J. Kehoe IV

Created: 2012-04-11 19:40:11 UTC

Size: 2.07 KB

patch

obsolete

>--- book.sgml.old	2012-04-11 13:34:36.000000000 -0400
>+++ book.sgml	2012-04-11 14:27:09.000000000 -0400
>@@ -3843,6 +3843,56 @@
> 	  may be able to save a large number of people&mdash;including
> 	  yourself&mdash; a lot of grief in the process.</para>
>       </sect2>
>+
>+      <sect2>
>+	<title>Automatic Detection Causes Problems</title>
>+
>+	<para>Dependencies must be declared either explicitly or by
>+	  using the <link
>+	    linkend="makefile-options">OPTIONS framework</link>.
>+	  Using other methods like automatic detection complicates
>+	  indexing, which causes problems for port and package
>+	  management.</para>
>+
>+	<example>
>+	  <title>Wrong Declaration of an Optional Dependency</title>
>+
>+	  <programlisting>.include &lt;bsd.port.pre.mk&gt;
>+
>+.if exists(${LOCALBASE}/bin/foo)
>+LIB_DEPENDS=	bar:${PORTSDIR}/foo/bar
>+.endif</programlisting>
>+	</example>
>+
>+	<para>The problem with the above method is that it declares a
>+	  dependency based on the existence of a file that may have
>+	  been installed by another port.  If all options were
>+	  recursively defined for a batch of ports and an index of
>+	  these ports was built, then the index would become
>+	  inconsistent during the installation of this batch if one of
>+	  its ports installed that file.  A new index would need to be
>+	  created, but it too may be inconsistent if there are other
>+	  ports that use this same method.</para>
>+
>+	<example>
>+	  <title>Correct Declaration of an Optional Dependency</title>
>+
>+	  <programlisting>OPTIONS=		BAR	"Enable bar support" on
>+
>+.include &lt;bsd.port.pre.mk&gt;
>+
>+.if defined(WITH_BAR) && !defined(WITHOUT_BAR)
>+LIB_DEPENDS=	bar:${PORTSDIR}/foo/bar
>+.endif</programlisting>
>+	</example>
>+
>+	<para>This second method is correct because it would not cause
>+	  inconsistencies in the index of a batch of ports, provided
>+	  the batch's options were defined prior to the index's build.
>+	  This makes it possible to use simple scripts to automate the
>+	  building, installation, and updating of these ports and
>+	  their packages.</para>
>+      </sect2>
>     </sect1>
> 
>     <sect1 id="makefile-masterdir">

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