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<TIP number='330'>
<header><title>Eliminate interp-&gt;result from the Public Headers</title><author address="mailto:kennykb@acm.org">Kevin B. Kenny</author><status type='project' state='final' tclversion="8.6" vote='after'>$Revision: 1.5 $</status><history></history><created day='22' month='sep' year='2008' /></header>
<abstract>This TIP proposes to eliminate the long-deprecated <emph style="italic">interp</emph>-&gt;<emph style="italic">result</emph> field from the public headers.</abstract>
<body><section title="Proposal">
<para>The include file <emph style="italic">tcl.h</emph> is to be modified so that the <emph style="italic">result</emph> field of the <emph style="italic">Tcl_Interp</emph> data structure will be renamed to <emph style="italic">unused1</emph> unless a preprocessor symbol, <emph style="bold">USE_INTERP_RESULT</emph> is defined.</para>
<para>Note that this change leaves the <emph style="italic">result</emph> field in the internal <emph style="italic">Interp</emph> data structure untouched, and all the code that manipulates it will still be there. Stubs compatiblity is thus preserved for extensions that compile against an 8.5 or earlier code base, and full source-level compatibility is available with the appropriate preprocessor definition.</para>
</section>
<section title="Rationale">
<para>The <emph style="italic">result</emph> field in this structure has been deprecated for a decade now, and yet extensions that use it still turn up. Extension writers need to be put on sterner notice that it <emph style="italic">will</emph> disappear as soon as Tcl 9.0 development is open.</para>
</section>
<section title="Copyright">
<para>Copyright © 2008 by Kevin B. Kenny.</para>
<para>This document may be distributed subject to the terms and conditions set forth in the Open Publication License, version 1.0 [<url ref="http://www.opencontent.org/openpub/"/>].</para>
</section>
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