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Traditionally the wayto deal with this is to <EM>know</EM> what the dependencies are and, whenlinking an executable, be careful to list all of the dependencies on thelink line in the correct order. If you have ever built an X Windowapplication using a widget library, you will already be familiar withthis notion.</P><P>Even though you only use the functions in the widget library directly, atypical link command would need to be:</P><P><TABLE><tr><td> </td><td class=smallexample><FONT SIZE=-1><pre>$ gcc -o Xtest -I/usr/X11R6/include Xtest.c -L/usr/X11R6/lib \-lXm -lXp -lXaw -lXmu -lX11 -lnsl -lsocket</FONT></pre></td></tr></table></P><P>With modern architectures, this problem has been solved by allowinglibraries to be linked into other libraries, but this feature is not yetparticularly portable. If you are trying to write a portable project,it is not safe to rely on native support for inter-library dependencies,especially if you want to have dependencies between static and sharedarchives. Some of the features discussed in this section were not fullyimplemented before Libtool 1.4, so you should make sure that you areusing this version or newer if you need these features.</P><P><BLOCKQUOTE>If you want to try the examples in this section to see what<CODE>libtool</CODE> does on your machine, you will first need to modifythe source of <TT>`hello.c'</TT> to introduce a dependency on <TT>`trim.c'</TT>: <P><TABLE><tr><td> </td><td class=smallexample><FONT SIZE=-1><pre></FONT></pre></td></tr></table></P><P>You might also want to modify the <TT>`main.c'</TT> file to exercise the new<SAMP>`trim'</SAMP> functionality to prove that the newly linked executable isworking:</P><P><TABLE><tr><td> </td><td class=smallexample><FONT SIZE=-1><pre></FONT></pre></td></tr></table></BLOCKQUOTE><P>Suppose I want to make two libraries, <TT>`libtrim'</TT> and<TT>`libhello'</TT>. <TT>`libhello'</TT> uses the <SAMP>`trim'</SAMP> function in<TT>`libtrim'</TT> but the code in <TT>`main'</TT> uses only the <SAMP>`hello'</SAMP>function in <TT>`libhello'</TT>. Traditionally, the two libraries are builtlike this:</P><P><TABLE><tr><td> </td><td class=smallexample><FONT SIZE=-1><pre>$ rm hello *.a *.la *.o *.lo$ gcc -c trim.c$ lshello.c main.c trim.c trim.o$ ar cru libtrim.a trim.o$ ranlib libtrim.a$ gcc -c hello.c$ lshello.c hello.o libtrim.a main.c trim.c trim.o$ ar cru libhello.a hello.o$ ranlib libhello.a$ lshello.c libhello.a main.c trim.ohello.o libtrim.a trim.c</FONT></pre></td></tr></table></P><P>Notice that there is no way to specify that <TT>`libhello.a'</TT> won't workunless it is also linked with <TT>`libtrim.a'</TT>. Because of this I needto list both libraries when I link the application. What's more, I needto list them in the correct order:</P><P><TABLE><tr><td> </td><td class=smallexample><FONT SIZE=-1><pre>$ gcc -o hello main.c libtrim.a libhello.a/usr/bin/ld: Unsatisfied symbols: trim (code)collect2: ld returned 1 exit status$ gcc -o hello main.c libhello.a libtrim.a$ lshello hello.o libtrim.a trim.chello.c libhello.a main.c trim.o$ ./helloHello, World!</FONT></pre></td></tr></table></P><P><A NAME="Inter-library Dependencies"></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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