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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: Testing system features at application runtime</TITLE><META NAME="description" CONTENT="Autoconf, Automake, and Libtool: Testing system features at application runtime"><META NAME="keywords" CONTENT="Autoconf, Automake, and Libtool: Testing system features at application runtime"><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; 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Keep in mind that the results of tests thatAutoconf can perform will ultimately affect how the program will bebuilt--and can limit the number of machines that the program can bemoved to without recompiling it. Here is an example where thisconsideration had to be made in a real life project:</P><P>The pthreads for Win32 project has sought to provide a standardscompliant implementation for the POSIX threads API. It doesso by mapping the POSIX API functions into small functionswhich achieve the desired result using the Win32 thread API.Windows 95, Windows 98 and Windows NT have different levels of supportfor a system call primitive that attempts to enter a critical sectionwithout blocking. The <CODE>TryEnterCriticalSection</CODE> function ismissing on Windows 95, is an inoperative stub on Windows 98, and worksas expected on Windows NT. If this behavior was to be checked by<TT>`configure'</TT> at compile time, then the resultant library would onlywork on the variant of Windows that it was compiled for. Because it'smore common to distribute packages for Windows in binary form, thiswould be an unfortunate situation. Instead, it is sometimes preferableto handle this kind of portability problem with a test, performed byyour code at runtime.</P><P><A NAME="Output from 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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