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<HTML><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><!-- Created on September, 12 2004 by texi2html 1.64 --><!-- Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author) Karl Berry <karl@freefriends.org> Olaf Bachmann <obachman@mathematik.uni-kl.de> and many others.Maintained by: Olaf Bachmann <obachman@mathematik.uni-kl.de>Send bugs and suggestions to <texi2html@mathematik.uni-kl.de> --><HEAD><TITLE>Autoconf, Automake, and Libtool: Reusing Existing Macros</TITLE><META NAME="description" CONTENT="Autoconf, Automake, and Libtool: Reusing Existing Macros"><META NAME="keywords" CONTENT="Autoconf, Automake, and Libtool: Reusing Existing Macros"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><META NAME="Generator" CONTENT="texi2html 1.64"><script language="Javascript"><!-- // Check the browser version. function checkVersion() { if (navigator.appVersion.charAt(0)>=3) return true; if (navigator.appVersion.charAt(0)>=4) return true; 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Amacro that wants to test for support of a new language keyword, forexample, should rely on the <CODE>AC_TRY_COMPILE</CODE> macro. This macro canbe used to attempt to compile a small program and detect a failure dueto, say, a syntax error.</P><P>In any case, it is good practice when reusing macros to adhere to theirpublicized interface--do not rely on implementation details such asshell variables used to record the test's result unless this isexplicitly mentioned as part of the macro's behavior. Macros in theAutoconf core can, and do, change their implementation from time totime.</P><P>Reusing a macro does not imply that the macro is necessarily invokedfrom within the definition of your macro. Sometimes you might just wantto rely on some action performed by a macro earlier in the configurationrun--this is still a form of reuse. In these cases, it is necessary toensure that this macro has indeed run at least once before your macro isinvoked. It is possible to state such a dependency by invoking the<CODE>AC_REQUIRE</CODE> macro at the beginning of your macro's definition.</P><P>Should you need to write a macro from scratch, the following sectionswill provide guidelines for writing better macros.</P><P><A NAME="Guidelines for writing macros"></A></TR></TABLE><BR> <FONT SIZE="-1">This document was generatedby <I>Gary V. Vaughan</I> on <I>September, 12 2004</I>using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html"><I>texi2html</I></A></BODY></HTML>⌨️ 快捷键说明
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