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<!-- Copyright (C) 2003 Red Hat, Inc. --> <!-- This material may be distributed only subject to the terms --> <!-- and conditions set forth in the Open Publication License, v1.0 --> <!-- or later (the latest version is presently available at --> <!-- http://www.opencontent.org/openpub/). --> <!-- Distribution of the work or derivative of the work in any --> <!-- standard (paper) book form is prohibited unless prior --> <!-- permission is obtained from the copyright holder. --> <HTML ><HEAD ><TITLE >parent</TITLE ><meta name="MSSmartTagsPreventParsing" content="TRUE"> <META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="The eCos Component Writer's Guide" HREF="cdl-guide.html"><LINK REL="UP" TITLE="CDL Language Specification" HREF="reference.html"><LINK REL="PREVIOUS" TITLE="no_define" HREF="ref.no-define.html"><LINK REL="NEXT" TITLE="requires" HREF="ref.requires.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >The <SPAN CLASS="APPLICATION" >eCos</SPAN > Component Writer's Guide</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="ref.no-define.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="ref.requires.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="REF.PARENT"><SPAN CLASS="PROPERTY" >parent</SPAN ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN4877" ></A ><H2 >Name</H2 >Property <SPAN CLASS="PROPERTY" >parent</SPAN > -- Control the location of an option in the configuration hierarchy.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN4881"><H2 >Synopsis</H2 ><TABLE BORDER="5" BGCOLOR="#E0E0F0" WIDTH="70%" ><TR ><TD ><PRE CLASS="SYNOPSIS" >cdl_option <name> { parent <component or package> … }</PRE ></TD ></TR ></TABLE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4883" ></A ><H2 >Description</H2 ><P >Configuration options live in a hierarchy of packages and components. By default a given option's position in the hierarchy is a simple consequence of its position within the CDL scripts. Packages are generally placed at the top-level of the configuration. Any components or options that are defined at the same level as the <TT CLASS="LITERAL" >cdl_package</TT > command in a package's top-level CDL script are placed immediately below that package in the hierarchy. Any options or components that are defined in the body of a <TT CLASS="LITERAL" >cdl_package</TT > or <TT CLASS="LITERAL" >cdl_component</TT > command, or that are read in as a result of processing a component's <SPAN CLASS="PROPERTY" >script</SPAN > property, will be placed immediately below that package or component in the hierarchy.</P ><P >In some circumstances it is useful to specify an alternative position in the hierarchy for a given option. For example it is often convenient to re-parent device driver packages below <TT CLASS="VARNAME" >CYGPKG_IO</TT > in the configuration hierarchy, thus reducing the number of packages at the top level of the hierarchy and making navigation easier. The <SPAN CLASS="PROPERTY" >parent</SPAN > property can be used to achieve this. </P ><P >The <SPAN CLASS="PROPERTY" >parent</SPAN > property takes a single argument, which should be the name of a package or component. The body of a <TT CLASS="LITERAL" >cdl_option</TT > or other CDL entity can contain at most one <SPAN CLASS="PROPERTY" >parent</SPAN > property.</P ><P >Although the <SPAN CLASS="PROPERTY" >parent</SPAN > property affects an option's position in the overall hierarchy and hence whether or not that option is active, a re-parented option still belongs to the package that defines it. By default any <TT CLASS="LITERAL" >#define's</TT > will be exported to that package's configuration header file. Any <SPAN CLASS="PROPERTY" >compile</SPAN > properties can only reference source files present in that package, and it is not directly possible to cause some file in another package to be built by re-parenting. </P ><P >As a special case, if an empty string is specified for the parent then the option is placed at the top of the hierarchy, ahead of any packages which are not explicitly re-parented in this way. This facility is useful for configuration options such as global preferences and default compiler flags.</P ><DIV CLASS="TIP" ><BLOCKQUOTE CLASS="TIP" ><P ><B >Tip: </B >If an option is re-parented somewhere below another package and that other package is not actually loaded, the option is an orphan and its active/inactive state is undefined. In such cases it is a good idea for the owning package to require the presence of the other one. Unfortunately this technique does not work if a package as a whole is reparented below another one that has not been loaded: the package is orphaned so it may be automatically inactive, and hence any <SPAN CLASS="PROPERTY" >requires</SPAN > properties would have no effect.</P ></BLOCKQUOTE ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4905" ></A ><H2 >Example</H2 ><TABLE BORDER="5" BGCOLOR="#E0E0F0" WIDTH="70%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >cdl_package CYGPKG_HAL_I386 { display "i386 architecture" parent CYGPKG_HAL hardware include_dir cyg/hal define_header hal_i386.h … } cdl_component CYGBLD_GLOBAL_OPTIONS { display "Global build options" parent "" … }</PRE ></TD ></TR ></TABLE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4908" ></A ><H2 >See Also</H2 ><P >Property <A HREF="ref.script.html" ><SPAN CLASS="PROPERTY" >script</SPAN ></A >, commands <A HREF="ref.cdl-component.html" ><TT CLASS="LITERAL" >cdl_component</TT ></A > and <A HREF="ref.cdl-package.html" ><TT CLASS="LITERAL" >cdl_package</TT ></A >.</P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="ref.no-define.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="cdl-guide.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="ref.requires.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><SPAN CLASS="PROPERTY" >no_define</SPAN ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="reference.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><SPAN CLASS="PROPERTY" >requires</SPAN ></TD ></TR ></TABLE ></DIV ></BODY ></HTML >
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