svn commit: r39952 - head/en_US.ISO8859-1/books/porters-handbook

[Eitan Adler]

Author: eadler
Date: Tue Nov  6 13:11:15 2012
New Revision: 39952
URL: http://svnweb.freebsd.org/changeset/doc/39952

Log:
  Prefer a more obvious syntax but add a note explaining why one
  may prefer the empty() syntax.
  
  PR:		docs/172662
  Submitted by:	crees
  Approved by:	bcr (mentor)

Modified:
  head/en_US.ISO8859-1/books/porters-handbook/book.xml

Modified: head/en_US.ISO8859-1/books/porters-handbook/book.xml
==============================================================================
--- head/en_US.ISO8859-1/books/porters-handbook/book.xml	Tue Nov  6 13:11:13 2012	(r39951)
+++ head/en_US.ISO8859-1/books/porters-handbook/book.xml	Tue Nov  6 13:11:15 2012	(r39952)
@@ -4476,7 +4476,7 @@ RUN_DEPENDS+=	bar:${PORTSDIR}/bar/bar
 
 	  <example id ="ports-options-check-unset">
 	    <title>Check for Unset Port <makevar>OPTIONS</makevar></title>
-	    <programlisting>.if empty(PORT_OPTIONS:MEXAMPLES)
+	    <programlisting>.if ! ${PORT_OPTIONS:MEXAMPLES}
 CONFIGURE_ARGS+=--without-examples
 .endif</programlisting>
 	  </example>
@@ -4515,7 +4515,7 @@ CONFIGURE_ARGS+=	--without-postgres
 LIB_DEPENDS+=	icuuc:${PORTSDIR}/devel/icu
 .endif
 
-.if empty(PORT_OPTIONS:MEXAMPLES)
+.if ! ${PORT_OPTIONS:MEXAMPLES}
 CONFIGURE_ARGS+=	--without-examples
 .endif
 
@@ -4620,6 +4620,17 @@ CONFIGURE_ARGS+=	--disable-foo
 	  disabled.  The configure script does not enable related
 	  features in the application, despite library's presence in
 	  the system.</para>
+
+	<note>
+	  <para>Under some circumstances, the shorthand conditional
+	    syntax can cause problems with complex constructs.
+	    If you receive errors such as <literal>Malformed
+	      conditional</literal>, an alternative syntax can be
+	    used.</para>
+	  <programlisting>.if !empty(VARIABLE:MVALUE)
+# as an alternative to
+.if ${VARIABLE:MVALUE}</programlisting>
+	</note>
       </sect2>
     </sect1>