1 files changed, 73 insertions, 0 deletions
diff --git a/doc/user/sconf.sgml b/doc/user/sconf.sgml
index 2e2a698..997c97d 100644
--- a/doc/user/sconf.sgml
+++ b/doc/user/sconf.sgml
@@ -67,6 +67,28 @@
 
     <para>
 
+    &SCons; provides a number of basic checks,
+    as well as a mechanism for adding your own custom checks.
+
+    </para>
+
+    <para>
+
+    Note that &SCons; uses its own dependency
+    mechanism to determine when a check
+    needs to be run--that is,
+    &SCons; does not run the checks
+    every time it is invoked,
+    but caches the values returned by previous checks
+    and uses the cached values unless something has changed.
+    This saves a tremendous amount
+    of developer time while working on
+    cross-platform build issues.
+
+    </para>
+
+    <para>
+
     The next sections describe
     the basic checks that &SCons; supports,
     as well as how to add your own custom checks.
@@ -396,3 +418,54 @@
     </screen>
 
   </section>
+
+  <section>
+  <title>Not Configuring When Cleaning Targets</title>
+
+    <para>
+
+    Using multi-platform configuration
+    as described in the previous sections
+    will run the configuration commands
+    even when invoking
+    <userinput>scons -c</userinput>
+    to clean targets:
+
+    </para>
+
+    <screen>
+    % <userinput>scons -Q -c</userinput>
+    Checking for MyLibrary... ok
+    Removed foo.o
+    Removed foo
+    </screen>
+
+    <para>
+
+    Although running the platform checks
+    when removing targets doesn't hurt anything,
+    it's usually unnecessary.
+    You can avoid this by using the
+    &GetOption;(); method to
+    check whether the <option>-c</option> (clean)
+    option has been invoked on the command line:
+
+    </para>
+
+    <programlisting>
+    env = Environment()
+    if not env.GetOption('clean'):
+        conf = Configure(env, custom_tests = {'CheckMyLibrary' : CheckMyLibrary})
+        if not conf.CheckMyLibrary():
+            print 'MyLibrary is not installed!'
+            Exit(1)
+        env = conf.Finish()
+    </programlisting>
+
+    <screen>
+    % <userinput>scons -Q -c</userinput>
+    Removed foo.o
+    Removed foo
+    </screen>
+
+  </section>