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><H1
><A
NAME="REF.CDL-COMPONENT"><TT
CLASS="LITERAL"
>cdl_component</TT
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN3091"
></A
><H2
>Name</H2
>Command <TT
CLASS="LITERAL"
>cdl_component</TT
> -- Define a component, a collection of configuration options</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN3095"><H2
>Synopsis</H2
><TABLE
BORDER="5"
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><TR
><TD
><PRE
CLASS="SYNOPSIS"
>cdl_component <name> {
…
}</PRE
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN3097"
></A
><H2
>Description</H2
><P
>A component is a configuration option that can contain additional
options and sub-components. The body of a <TT
CLASS="LITERAL"
>cdl_component</TT
> can contain
the same properties as that of a <TT
CLASS="LITERAL"
>cdl_option</TT
>. There is an additional
property, <SPAN
CLASS="PROPERTY"
>script</SPAN
> which allows configuration data to be split into
multiple files. It is also possible for a component body to include
<TT
CLASS="LITERAL"
>cdl_component</TT
>, <TT
CLASS="LITERAL"
>cdl_option</TT
> and <TT
CLASS="LITERAL"
>cdl_interface</TT
> entities that should
go below this component in the configuration hierarchy.</P
><P
><TT
CLASS="LITERAL"
>cdl_component</TT
> is implemented as a Tcl command that takes two
arguments, a name and a body. The name must be a valid C preprocessor
identifier: a sequence of upper or lower case letters, digits or
underscores, starting with a non-digit character; identifiers
beginning with an underscore should normally be avoided because they
may clash with system packages or with identifiers reserved for use by
the compiler. Within a single configuration, names must be unique. If
a configuration contained two packages which defined the same entity
<TT
CLASS="LITERAL"
>CYGIMP_SOME_OPTION</TT
>, any references to that entity
in a <SPAN
CLASS="PROPERTY"
>requires</SPAN
> property or any other expression would be ambiguous.
It is possible for a given name to be used by two different packages
if those packages should never be loaded into a single configuration.
For example, architectural HAL packages are allowed to re-use certain
names because a single configuration cannot target two different
architectures. For a recommended naming convention see <A
HREF="package.contents.html"
>the Section called <I
>Package Contents and Layout</I
> in Chapter 2</A
>.</P
><P
>The second argument to <TT
CLASS="LITERAL"
>cdl_component</TT
> is a body of properties and
other commands, typically surrounded by braces so that the Tcl
interpreter treats it as a single argument. This body will be
processed by a recursive invocation of the Tcl interpreter, extended
with additional commands for the various properties that are allowed
inside a <TT
CLASS="LITERAL"
>cdl_component</TT
>. The valid commands are:</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><A
HREF="ref.active-if.html"
><SPAN
CLASS="PROPERTY"
>active_if</SPAN
></A
></DT
><DD
><P
>Allow additional control over the active state of this component.</P
></DD
><DT
><A
HREF="ref.calculated.html"
><SPAN
CLASS="PROPERTY"
>calculated</SPAN
></A
></DT
><DD
><P
>The component's value is not directly user-modifiable, it is calculated
using a suitable CDL expression.</P
></DD
><DT
><A
HREF="ref.cdl-component.html"
><TT
CLASS="LITERAL"
>cdl_component</TT
></A
></DT
><DD
><P
>Define a sub-component.</P
></DD
><DT
><A
HREF="ref.cdl-interface.html"
><TT
CLASS="LITERAL"
>cdl_interface</TT
></A
></DT
><DD
><P
>Define an interface which should appear immediately below this
component in the configuration hierarchy.</P
></DD
><DT
><A
HREF="ref.cdl-option.html"
><TT
CLASS="LITERAL"
>cdl_option</TT
></A
></DT
><DD
><P
>Define a configuration option which should appear immediately below
this component in the configuration hierarchy.</P
></DD
><DT
><A
HREF="ref.compile.html"
><SPAN
CLASS="PROPERTY"
>compile</SPAN
></A
></DT
><DD
><P
>List the source files that should be built if this component is active
and enabled.</P
></DD
><DT
><A
HREF="ref.default-value.html"
><SPAN
CLASS="PROPERTY"
>default_value</SPAN
></A
></DT
><DD
><P
>Provide a default value for this component using a CDL expression.</P
></DD
><DT
><A
HREF="ref.define.html"
><SPAN
CLASS="PROPERTY"
>define</SPAN
></A
></DT
><DD
><P
>Specify additional <TT
CLASS="LITERAL"
>#define</TT
> symbols that should go
into the owning package's configuration header file.</P
></DD
><DT
><A
HREF="ref.define-format.html"
><SPAN
CLASS="PROPERTY"
>define_format</SPAN
></A
></DT
><DD
><P
>Control how the component's value will appear in the configuration header
file.</P
></DD
><DT
><A
HREF="ref.define-proc.html"
><SPAN
CLASS="PROPERTY"
>define_proc</SPAN
></A
></DT
><DD
><P
>Use a fragment of Tcl code to output additional data to
configuration header files.</P
></DD
><DT
><A
HREF="ref.description.html"
><SPAN
CLASS="PROPERTY"
>description</SPAN
></A
></DT
><DD
><P
>Provide a textual description for this component.</P
></DD
><DT
><A
HREF="ref.display.html"
><SPAN
CLASS="PROPERTY"
>display</SPAN
></A
></DT
><DD
><P
>Provide a short string describing this component.</P
></DD
><DT
><A
HREF="ref.doc.html"
><SPAN
CLASS="PROPERTY"
>doc</SPAN
></A
></DT
><DD
><P
>The location of on-line documentation for this component.</P
></DD
><DT
><A
HREF="ref.flavor.html"
><SPAN
CLASS="PROPERTY"
>flavor</SPAN
></A
></DT
><DD
><P
>Specify the nature of this component.</P
></DD
><DT
><A
HREF="ref.if-define.html"
><SPAN
CLASS="PROPERTY"
>if_define</SPAN
></A
></DT
><DD
><P
>Output a common preprocessor construct to a configuration header file. </P
></DD
><DT
><A
HREF="ref.implements.html"
><SPAN
CLASS="PROPERTY"
>implements</SPAN
></A
></DT
><DD
><P
>Enabling this component provides one instance of a more general
interface. </P
></DD
><DT
><A
HREF="ref.legal-values.html"
><SPAN
CLASS="PROPERTY"
>legal_values</SPAN
></A
></DT
><DD
><P
>Impose constraints on the possible values for this component.</P
></DD
><DT
><A
HREF="ref.make.html"
><SPAN
CLASS="PROPERTY"
>make</SPAN
></A
></DT
><DD
><P
>An additional custom build step associated with this component, resulting
in a target that should not go directly into a library.</P
></DD
><DT
><A
HREF="ref.make-object.html"
><SPAN
CLASS="PROPERTY"
>make_object</SPAN
></A
></DT
><DD
><P
>An additional custom build step associated with this component, resulting
in an object file that should go into a library.</P
></DD
><DT
><A
HREF="ref.no-define.html"
><SPAN
CLASS="PROPERTY"
>no_define</SPAN
></A
></DT
><DD
><P
>Suppress the normal generation of a preprocessor
<TT
CLASS="LITERAL"
>#define</TT
> symbol in a configuration header file.</P
></DD
><DT
><A
HREF="ref.parent.html"
><SPAN
CLASS="PROPERTY"
>parent</SPAN
></A
></DT
><DD
><P
>Control the location of this component in the configuration hierarchy. </P
></DD
><DT
><A
HREF="ref.requires.html"
><SPAN
CLASS="PROPERTY"
>requires</SPAN
></A
></DT
><DD
><P
>List constraints that the configuration should satisfy if this component is
active and enabled.</P
></DD
><DT
><A
HREF="ref.script.html"
><SPAN
CLASS="PROPERTY"
>script</SPAN
></A
></DT
><DD
><P
>Include additional configuration information from another
CDL script</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN3255"
></A
><H2
>Example</H2
><P
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>cdl_component CYGDBG_USE_ASSERTS {
display "Use asserts"
default_value 1
description "
If this component is enabled, assertions in the code are
tested at run-time. Assert functions (CYG_ASSERT()) are
defined in 'include/cyg/infra/cyg_ass.h' within the 'install'
tree. If the component is disabled, these result in no
additional object code and no checking of the asserted
conditions."
script assert.cdl
}</PRE
></TD
></TR
></TABLE
></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN3259"
></A
><H2
>See Also</H2
><P
>Command <A
HREF="ref.cdl-option.html"
><TT
CLASS="LITERAL"
>cdl_option</TT
></A
>,
command <A
HREF="ref.cdl-package.html"
><TT
CLASS="LITERAL"
>cdl_package</TT
></A
>,
command <A
HREF="ref.cdl-interface.html"
><TT
CLASS="LITERAL"
>cdl_interface</TT
></A
>.</P
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