+++ /dev/null
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-><HEAD
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->flavor</TITLE
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-><BODY
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-> Component Writer's Guide</TH
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-><HR
-ALIGN="LEFT"
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-><H1
-><A
-NAME="REF.FLAVOR"><SPAN
-CLASS="PROPERTY"
->flavor</SPAN
-></H1
-><DIV
-CLASS="REFNAMEDIV"
-><A
-NAME="AEN4315"
-></A
-><H2
->Name</H2
->Property <SPAN
-CLASS="PROPERTY"
->flavor</SPAN
-> -- Specify the nature of a configuration option.</DIV
-><DIV
-CLASS="REFSYNOPSISDIV"
-><A
-NAME="AEN4319"><H2
->Synopsis</H2
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="SYNOPSIS"
->cdl_option <name> {
- flavor <flavor>
- …
-}</PRE
-></TD
-></TR
-></TABLE
-></DIV
-><DIV
-CLASS="REFSECT1"
-><A
-NAME="AEN4321"
-></A
-><H2
->Description</H2
-><P
->The state of a <SPAN
-CLASS="APPLICATION"
->CDL</SPAN
-> configuration option is a somewhat complicated
-concept. This state determines what happens when a build tree is
-generated: it controls what files get built and what
-<TT
-CLASS="LITERAL"
->#define's</TT
-> end up in configuration header files. The
-state also controls the values used during expression evaluation. The
-key concepts are:</P
-><P
-></P
-><OL
-TYPE="1"
-><LI
-><P
->An option may or may not be loaded into the current configuration.
-However it is still possible for packages to reference options which
-are not loaded in a <SPAN
-CLASS="PROPERTY"
->requires</SPAN
-> constraint or other expression. If an
-option is not loaded then it will have no direct effect on the build
-process, and <TT
-CLASS="LITERAL"
->0</TT
-> will be used for expression
-evaluation. </P
-></LI
-><LI
-><P
->Even if an option is loaded it may still be inactive. Usually this is
-controlled by the option's location in the configuration hierarchy. If
-an option's parent is active and enabled then the option will normally
-be active. If the parent is either inactive or disabled then the
-option will be inactive. For example, if kernel timeslicing is diabled
-then the option <TT
-CLASS="LITERAL"
->CYGNUM_KERNEL_SCHED_TIMESLICE_TICKS</TT
->
-is irrelevant and must have no effect. The <SPAN
-CLASS="PROPERTY"
->active_if</SPAN
-> property can be
-used to specify additional constraints. If an option is inactive then
-it will have no direct effect on the build process, in other words it
-will not cause any files to get built or <TT
-CLASS="LITERAL"
->#define's</TT
->
-to be generated. For the purposes of expression evaluation an inactive
-option has a value of <TT
-CLASS="LITERAL"
->0</TT
->.</P
-></LI
-><LI
-><P
->An option may be enabled or disabled. Most options are boolean in
-nature, for example a particular function may get inlined or it may
-involve a full procedure call. If an option is disabled then it has no
-direct effect on the build process, and for the purposes of expression
-evaluation it has a value of 0.</P
-></LI
-><LI
-><P
->An option may also have additional data associated with it, for
-example a numerical value used to control the size of an array.</P
-></LI
-></OL
-><P
->Most options are boolean in nature and do not have any additional
-associated data. For some options only the data part makes sense and
-users should be unable to manipulate the enabled/disabled part of the
-state. For a comparatively small number of options it makes sense to
-have the ability to disable that option or to enable it and associate
-data as well. Finally, when constructing an option hierarchy it is
-occasionally useful to have entities which serve only as placeholders.
-The <SPAN
-CLASS="PROPERTY"
->flavor</SPAN
-> property can be used to control all this. There are four
-possible values. It should be noted that the active or inactive state
-of an option takes priority over the flavor: if an option is inactive
-then no <TT
-CLASS="LITERAL"
->#define's</TT
-> will be generated and any
-build-related properties such as <SPAN
-CLASS="PROPERTY"
->compile</SPAN
-> will be ignored.</P
-><P
-></P
-><DIV
-CLASS="VARIABLELIST"
-><DL
-><DT
->flavor <TT
-CLASS="LITERAL"
->none</TT
-></DT
-><DD
-><P
->The <TT
-CLASS="LITERAL"
->none</TT
-> is intended primarily for placeholder
-components in the hierarchy, although it can be used for other
-purposes. Options with this flavor are always enabled and do not have
-any additional data associated with them, so there is no way for users
-to modify the option. For the purposes of expression evaluation an
-option with flavor <TT
-CLASS="LITERAL"
->none</TT
-> always has the value
-<TT
-CLASS="LITERAL"
->1</TT
->. Normal <TT
-CLASS="LITERAL"
->#define</TT
-> processing
-will take place, so typically a single <TT
-CLASS="LITERAL"
->#define</TT
-> will
-be generated using the option name and a value of
-<TT
-CLASS="LITERAL"
->1</TT
->. Similarly build-related properties such as
-<SPAN
-CLASS="PROPERTY"
->compile</SPAN
-> will take effect.</P
-></DD
-><DT
->flavor <TT
-CLASS="LITERAL"
->bool</TT
-></DT
-><DD
-><P
->Boolean options can be either enabled or disabled, and there is no
-additional data associated with them. If a boolean option is disabled
-then no <TT
-CLASS="LITERAL"
->#define</TT
-> will be generated and any
-build-related properties such as <SPAN
-CLASS="PROPERTY"
->compile</SPAN
-> will be ignored. For the
-purposes of expression evaluation a disabled option has the value
-<TT
-CLASS="LITERAL"
->0</TT
->. If a boolean option is enabled then normal
-<TT
-CLASS="LITERAL"
->#define</TT
-> processing will take place, all
-build-related properties take effect, and the option's value will be
-<TT
-CLASS="LITERAL"
->1</TT
->.</P
-></DD
-><DT
->flavor <TT
-CLASS="LITERAL"
->data</TT
-></DT
-><DD
-><P
->Options with this flavor are always enabled, and have some additional
-data associated with them which can be edited by the user. This data
-can be any sequence of characters, although in practice the
-<SPAN
-CLASS="PROPERTY"
->legal_values</SPAN
-> property will often be used to impose constraints. In
-appropriate contexts such as expressions the configuration tools will
-attempt to interpret the data as integer or floating point numbers.
-Since an option with the <TT
-CLASS="LITERAL"
->data</TT
-> flavor cannot be
-disabled, normal <TT
-CLASS="LITERAL"
->#define</TT
-> processing takes place and
-the data will be used for the value. Similarly all build-related
-properties take effect, and the option's value for the purposes of
-expression evaluation is the data.</P
-></DD
-><DT
->flavor <TT
-CLASS="LITERAL"
->booldata</TT
-></DT
-><DD
-><P
->This combines the <TT
-CLASS="LITERAL"
->bool</TT
-> and <TT
-CLASS="LITERAL"
->data</TT
->
-flavors. The option may be enabled or disabled, and in addition the
-option has some associated data. If the option is disabled then no
-<TT
-CLASS="LITERAL"
->#define</TT
-> will be generated, the build-related
-properties have no effect, and for the purposes of expression
-evaluation the option's value is <TT
-CLASS="LITERAL"
->0</TT
->. If the option
-is enabled then a <TT
-CLASS="LITERAL"
->#define</TT
-> will be generated using
-the data as the value, all build-related properties take effect, and
-the option's value for the purposes of expression evaluation is the
-data. If <TT
-CLASS="LITERAL"
->0</TT
-> is legal data then it is not possible to
-distinguish this case from the option being disabled or inactive.</P
-></DD
-></DL
-></DIV
-><P
->Options and components have the <TT
-CLASS="LITERAL"
->bool</TT
-> flavor by
-default, but this can be changed as desired. Packages always have the
-<TT
-CLASS="LITERAL"
->booldata</TT
-> flavor, and this cannot be changed.
-Interfaces have the <TT
-CLASS="LITERAL"
->data</TT
-> flavor by default, since
-the value of an interface is a count of the number of active and
-enabled interfaces, but they can be given the <TT
-CLASS="LITERAL"
->bool</TT
->
-or <TT
-CLASS="LITERAL"
->booldata</TT
-> flavors.</P
-><DIV
-CLASS="NOTE"
-><BLOCKQUOTE
-CLASS="NOTE"
-><P
-><B
->Note: </B
->The expression syntax needs to be extended to allow the loaded,
-active, enabled and data aspects of an option's state to be examined
-individually. This would allow component writers to distinguish
-between a disabled <TT
-CLASS="LITERAL"
->booldata</TT
-> option and an enabled
-one which has a value of <TT
-CLASS="LITERAL"
->0</TT
->. Such an enhancement to
-the expression syntax may also prove useful in other circumstances.</P
-></BLOCKQUOTE
-></DIV
-></DIV
-><DIV
-CLASS="REFSECT1"
-><A
-NAME="AEN4397"
-></A
-><H2
->Example</H2
-><TABLE
-BORDER="5"
-BGCOLOR="#E0E0F0"
-WIDTH="70%"
-><TR
-><TD
-><PRE
-CLASS="PROGRAMLISTING"
-> cdl_component CYGPKG_LIBM_COMPATIBILITY {
-
- cdl_component CYGNUM_LIBM_COMPATIBILITY {
- flavor booldata
- …
-
- cdl_option CYGNUM_LIBM_COMPAT_DEFAULT {
- flavor data
- …
- }
- }
-
- …
-}
-
-cdl_component CYGPKG_LIBM_TRACE {
- flavor bool
- …
-}</PRE
-></TD
-></TR
-></TABLE
-></DIV
-><DIV
-CLASS="REFSECT1"
-><A
-NAME="AEN4400"
-></A
-><H2
->See Also</H2
-><P
->Properties <A
-HREF="ref.calculated.html"
-><SPAN
-CLASS="PROPERTY"
->calculated</SPAN
-></A
->,
-<A
-HREF="ref.default-value.html"
-><SPAN
-CLASS="PROPERTY"
->default_value</SPAN
-></A
-> and
-<A
-HREF="ref.legal-values.html"
-><SPAN
-CLASS="PROPERTY"
->legal_values</SPAN
-></A
->,</P
-></DIV
-><DIV
-CLASS="NAVFOOTER"
-><HR
-ALIGN="LEFT"
-WIDTH="100%"><TABLE
-SUMMARY="Footer navigation table"
-WIDTH="100%"
-BORDER="0"
-CELLPADDING="0"
-CELLSPACING="0"
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-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
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-HREF="ref.doc.html"
-ACCESSKEY="P"
->Prev</A
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-WIDTH="34%"
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-HREF="cdl-guide.html"
-ACCESSKEY="H"
->Home</A
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-WIDTH="33%"
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->Next</A
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