doc/html/cdl-guide/ref.implements.html

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  85 NAME="REF.IMPLEMENTS"><SPAN
  86 CLASS="PROPERTY"
  87 >implements</SPAN
  88 ></H1
  89 ><DIV
  90 CLASS="REFNAMEDIV"
  91 ><A
  92 NAME="AEN4507"
  93 ></A
  94 ><H2
  95 >Name</H2
  96 >Property <SPAN
  97 CLASS="PROPERTY"
  98 >implements</SPAN
  99 >&nbsp;--&nbsp;Enabling this option provides one instance of a more
 100 general interface.</DIV
 101 ><DIV
 102 CLASS="REFSYNOPSISDIV"
 103 ><A
 104 NAME="AEN4511"><H2
 105 >Synopsis</H2
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 111 ><TD
 112 ><PRE
 113 CLASS="SYNOPSIS"
 114 >cdl_option &lt;name&gt; {
 115     implements &lt;interface&gt;
 116     &#8230;
 117 }</PRE
 118 ></TD
 119 ></TR
 120 ></TABLE
 121 ></DIV
 122 ><DIV
 123 CLASS="REFSECT1"
 124 ><A
 125 NAME="AEN4513"
 126 ></A
 127 ><H2
 128 >Description</H2
 129 ><P
 130 >The <SPAN
 131 CLASS="APPLICATION"
 132 >CDL</SPAN
 133 > interface concept provides an abstraction mechanism that can
 134 be useful in many different circumstances. Essentially an interface is
 135 a calculated option whose value is the number of active and enabled
 136 options which implement that interface. For example the interface
 137 <TT
 138 CLASS="VARNAME"
 139 >CYGINT_KERNEL_SCHEDULER</TT
 140 > has a value corresponding
 141 to the number of schedulers in the system, typically just one.</P
 142 ><P
 143 >The <SPAN
 144 CLASS="PROPERTY"
 145 >implements</SPAN
 146 > property takes a single argument, which should be the
 147 name of an interface. This interface may be defined in the same
 148 package as the implementor or in some other package. In the latter
 149 case it may sometimes be appropriate for the implementor or the
 150 implementor's package to have a <SPAN
 151 CLASS="PROPERTY"
 152 >requires</SPAN
 153 > property for the package
 154 containing the interface. An option may contain multiple <SPAN
 155 CLASS="PROPERTY"
 156 >implements</SPAN
 157 >
 158 properties. It is possible for an option to implement a given
 159 interface multiple times, and on occasion this is actually useful.</P
 160 ></DIV
 161 ><DIV
 162 CLASS="REFSECT1"
 163 ><A
 164 NAME="AEN4522"
 165 ></A
 166 ><H2
 167 >Example</H2
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 174 ><PRE
 175 CLASS="PROGRAMLISTING"
 176 >cdl_option CYGSEM_KERNEL_SCHED_MLQUEUE {
 177     display       "Multi-level queue scheduler"
 178     default_value 1
 179     implements    CYGINT_KERNEL_SCHEDULER
 180     &#8230;
 181 }</PRE
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 187 CLASS="REFSECT1"
 188 ><A
 189 NAME="AEN4525"
 190 ></A
 191 ><H2
 192 >See Also</H2
 193 ><P
 194 >Command <A
 195 HREF="ref.cdl-interface.html"
 196 ><TT
 197 CLASS="LITERAL"
 198 >cdl_interface</TT
 199 ></A
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