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POHow to call functions within order-only prerequisites?
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copied!<p>Given this bit of Makefile:</p> <pre><code># for pattern matching $(OBJDIR) := build # just to see if a level of indirection will work my_dir = $(dir $(1)) $(OBJECTS) : $(OBJDIR)/% : $(HEADERS) $(SRCDIR)/% | % $(dir %) $(call my_dir,%) @echo output-only = $| </code></pre> <p>This is a <a href="http://www.gnu.org/software/make/manual/make.html#Static-Pattern" rel="nofollow">static pattern rule</a> with <a href="http://www.gnu.org/software/make/manual/make.html#Prerequisite-Types" rel="nofollow">order-only prerequisites</a>.</p> <p>Consider the target "build/utility/debug.js". The output of the above rule will be this:</p> <pre><code>output-only = utility/debug.js ./ </code></pre> <ul> <li>The first component, "utility/debug.js", is properly copied from the stem (%).</li> <li>The second component, "./", is the output of calling the <code>dir</code> function in the prerequisites list.</li> <li>The third component, an empty string, is the output of calling my <code>my_dir</code> function in the prerequisites list.</li> </ul> <p>If I change <code>my_dir</code> to this:</p> <pre><code>my_dir = $(1) </code></pre> <p>The output remains the same. If I change it to this:</p> <pre><code>my_dir = "foo" </code></pre> <p>Then make complains there is no rule to make "foo" (which is expected). It appears, then, that <code>$(1)</code> is not getting bound in the call to <code>my_dir</code>.</p> <p>What's going on? Why can't I pass the stem to a function? I have a workaround that uses secondary expansion, but I want to know why I can't write my rule this way.</p> <p><strong>EDIT:</strong> I'm new to stackoverflow, forgive me if this is not the way things are done here.</p> <p>I want $(1) because I am passing the stem as an argument to <code>my_dir</code>, as Alex pointed out.</p> <p>I don't know why it was suggested I want "$". I don't believe $ by itself expands to anything in any context.</p> <p>I know that automatic variables are only available in the recipe. I am not using an automatic variable in the prerequisites - I am using the stem:</p> <blockquote> <p>Each target is matched against the target-pattern to extract a part of the target name, called the stem. This stem is substituted into each of the prereq-patterns to make the prerequisite names (one from each prereq-pattern). <a href="http://www.gnu.org/software/make/manual/make.html#Static-Usage" rel="nofollow">- the manual</a></p> </blockquote> <p>The fact that the stem is available is demonstrated by the example: the stem expands to the correct value when used alone, but not when passed to a function.</p>

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