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-><H1
-><A
-NAME="REF.CDL-OPTION"><TT
-CLASS="LITERAL"
->cdl_option</TT
-></H1
-><DIV
-CLASS="REFNAMEDIV"
-><A
-NAME="AEN2940"
-></A
-><H2
->Name</H2
->Command <TT
-CLASS="LITERAL"
->cdl_option</TT
-> -- Define a single configuration option</DIV
-><DIV
-CLASS="REFSYNOPSISDIV"
-><A
-NAME="AEN2944"><H2
->Synopsis</H2
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="SYNOPSIS"
->cdl_option <name> {
- …
-}</PRE
-></TD
-></TR
-></TABLE
-></DIV
-><DIV
-CLASS="REFSECT1"
-><A
-NAME="AEN2946"
-></A
-><H2
->Description</H2
-><P
->The option is the basic unit of configurability. Generally each option
-corresponds to a single user choice. Typically there is a certain
-amount of information associated with an option to assist the user in
-manipulating that option, for example a textual description. There
-will also be some limits on the possible values that the user can
-choose, so an option may be a simple yes-or-no choice or it may be
-something more complicated such as an array size or a device name.
-Options may have associated constraints, so if that option is enabled
-then certain conditions have to satisfied elsewhere in the
-configuration. Options usually have direct consequences such as
-preprocessor <TT
-CLASS="LITERAL"
->#define</TT
-> symbols in a configuration
-header file.</P
-><P
-><TT
-CLASS="LITERAL"
->cdl_option</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 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_option</TT
-> is a body of
-properties, 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_option</TT
->. The valid properties 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 option.</P
-></DD
-><DT
-><A
-HREF="ref.calculated.html"
-><SPAN
-CLASS="PROPERTY"
->calculated</SPAN
-></A
-></DT
-><DD
-><P
->The option's value is not directly user-modifiable, it is calculated
-using a suitable CDL expression.</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 option 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 option 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 option'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 option.</P
-></DD
-><DT
-><A
-HREF="ref.display.html"
-><SPAN
-CLASS="PROPERTY"
->display</SPAN
-></A
-></DT
-><DD
-><P
->Provide a short string describing this option.</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 option.</P
-></DD
-><DT
-><A
-HREF="ref.flavor.html"
-><SPAN
-CLASS="PROPERTY"
->flavor</SPAN
-></A
-></DT
-><DD
-><P
->Specify the nature of this option.</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 option 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 option.</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 option, 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 option, 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 option 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 option is
-active and enabled.</P
-></DD
-></DL
-></DIV
-></DIV
-><DIV
-CLASS="REFSECT1"
-><A
-NAME="AEN3075"
-></A
-><H2
->Example</H2
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="PROGRAMLISTING"
->cdl_option CYGDBG_INFRA_DEBUG_PRECONDITIONS {
- display "Preconditions"
- default_value 1
- description "
- This option allows individual control of preconditions.
- A precondition is one type of assert, which it is
- useful to control separately from more general asserts.
- The function is CYG_PRECONDITION(condition,msg)."
-}</PRE
-></TD
-></TR
-></TABLE
-></DIV
-><DIV
-CLASS="REFSECT1"
-><A
-NAME="AEN3078"
-></A
-><H2
->See Also</H2
-><P
->Command <A
-HREF="ref.cdl-component.html"
-><TT
-CLASS="LITERAL"
->cdl_component</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
-></DIV
-><DIV
-CLASS="NAVFOOTER"
-><HR
-ALIGN="LEFT"
-WIDTH="100%"><TABLE
-SUMMARY="Footer navigation table"
-WIDTH="100%"
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