codeblocks-ep/help/html/programmerHelp/make/Archive-Update.html at master · maifeeulasad/codeblocks-ep · GitHub

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<title>GNU `make'</title>
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<p>
Node:<a name="Archive%20Update">Archive Update</a>,
Next:<a rel="next" accesskey="n" href="Archive-Pitfalls.html#Archive%20Pitfalls">Archive Pitfalls</a>,
Previous:<a rel="previous" accesskey="p" href="Archive-Members.html#Archive%20Members">Archive Members</a>,
Up:<a rel="up" accesskey="u" href="Archives.html#Archives">Archives</a>
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<h3 class="section">Implicit Rule for Archive Member Targets</h3>

   <p>Recall that a target that looks like <code></code><var>a</var><code>(</code><var>m</var><code>)</code> stands for the
member named <var>m</var> in the archive file <var>a</var>.

   <p>When <code>make</code> looks for an implicit rule for such a target, as a special
feature it considers implicit rules that match <code>(</code><var>m</var><code>)</code>, as well as
those that match the actual target <code></code><var>a</var><code>(</code><var>m</var><code>)</code>.

   <p>This causes one special rule whose target is <code>(%)</code> to match.  This
rule updates the target <code></code><var>a</var><code>(</code><var>m</var><code>)</code> by copying the file <var>m</var>
into the archive.  For example, it will update the archive member target
<code>foo.a(bar.o)</code> by copying the <em>file</em> <code>bar.o</code> into the
archive <code>foo.a</code> as a <em>member</em> named <code>bar.o</code>.

   <p>When this rule is chained with others, the result is very powerful.
Thus, <code>make "foo.a(bar.o)"</code> (the quotes are needed to protect the
<code>(</code> and <code>)</code> from being interpreted specially by the shell) in
the presence of a file <code>bar.c</code> is enough to cause the following
commands to be run, even without a makefile:

<pre class="example">     cc -c bar.c -o bar.o
     ar r foo.a bar.o
     rm -f bar.o
     </pre>

<p>Here <code>make</code> has envisioned the file <code>bar.o</code> as an intermediate
file.  See <a href="Chained-Rules.html#Chained%20Rules">Chains of Implicit Rules</a>.

   <p>Implicit rules such as this one are written using the automatic variable
<code>$%</code>.  See <a href="Automatic.html#Automatic">Automatic Variables</a>.

   <p>An archive member name in an archive cannot contain a directory name, but
it may be useful in a makefile to pretend that it does.  If you write an
archive member target <code>foo.a(dir/file.o)</code>, <code>make</code> will perform
automatic updating with this command:

<pre class="example">     ar r foo.a dir/file.o
     </pre>

<p>which has the effect of copying the file <code>dir/file.o</code> into a member
named <code>file.o</code>.  In connection with such usage, the automatic variables
<code>%D</code> and <code>%F</code> may be useful.

<ul class="menu">
<li><a accesskey="1" href="Archive-Symbols.html#Archive%20Symbols">Archive Symbols</a>:              How to update archive symbol directories.
</ul>

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