mirrors
/
org.aspectj
mirror of https://github.com/eclipse/org.aspectj.git
Watch 1
Star 0
Fork 0
Code Issues 0 Releases 139 Wiki Activity
Browse Source

fixes

tags/V1_1_1
ehilsdal 21 years ago
parent
bfad02fdb1
commit
bb357e7c74
1 changed files with 61 additions and 116 deletions
Split View Show Diff Stats
  1. 61
    116
      docs/teaching/exercises/index.html

+ 61
- 116
docs/teaching/exercises/index.html View File

@@ -13,14 +13,14 @@ cases. They progress, as most users do in their adoption of AspectJ,
from non-functional, development-only aspects to aspects which augment
a deployed program with crosscutting features. </p>

<p> We have made available a package that includes the tests, the base
code, JUnit, and a distribution of AspectJ. All it needs is
information about where Java lives (so set your JAVA_HOME environment
variable). It assumes that you unzip it in c:\ (on Windows) or in
your home directory (on Linux): If you put it somewhere else, edit
setpaths or setpaths.bat, as appropriate. Once all this is done, run
<code>setpaths.bat</code> or <code>source setpaths</code> to export
some other needed environment variables. </p>
<p> Before the tutorial we will make available a package that includes
the tests, the base code, JUnit, and a distribution of AspectJ. All
it needs is information about where Java lives (so set your JAVA_HOME
environment variable). It assumes that you unzip it in c:\ (on
Windows) or in your home directory (on Linux): If you put it somewhere
else, edit setpaths or setpaths.bat, as appropriate. Once all this is
done, run <code>setpaths.bat</code> or <code>source setpaths</code> to
export some other needed environment variables. </p>

<p> All the files in the program are listed in base.lst, including
test cases and an empty answer aspect,
@@ -72,16 +72,39 @@ you go from one exercise to the next, make sure to save your work in a
file and go on to work in a different file, even if you plan to
duplicate some code. </p>

<h3>Environment</h3>

<p> You may use whatever editor or environment you choose to work
through these exercises. We provide a simple code-browser that can
work well as an editor for these short exercises, in addition to
providing better visualization of how aspects affect the system: </p>

<blockquote><PRE>
$ ajbrowser base.lst
</PRE></blockquote>

<p> With the browser you can edit code (including the
<code>answers/Answer.java</code> file), and after saving hit the build
button to start an ajc compile. We recommend you start up another
shell, though, to run the JUnit tests (and don't forget to run the
<code>setpaths</code> script when you open the new shell): You could
set up the run button to run a test through the Options menu, but
we've found this is fairly cumbersome. </p>


<hr>
<!-- page break -->
<!-- ============================== -->

<br style="page-break-after: always" />
<h2>1. Static Invariants</h2>

<h3>a. Catch old tracing</h3>

<p> <strong>Sample Exercise</strong>: The main point of this exercise
is to make sure your configuration works. We have provided the
answer to this exercise below, so XXX. You need not go through the
thought process of fixing this </p>
is to make sure your configuration works. Type in the answer below
into your answer file, make sure you get the desired compile-time
error, remove the offending line, and make sure you pass the JUnit
test. </p>

<p> <strong>Task:</strong> Signal a warning for calls to
<code>System.out.println</code>.
@@ -100,10 +123,9 @@ trace in <code>SlothfulPoint</code>.

<blockquote><PRE>
$ ajc -argfile base.lst
./figures/SlothfulPoint.java:29:9: illegal access to System.out
System.out.println("Slothful moving");
^
1 errors
./figures/SlothfulPoint.java:38 illegal access to System.out

1 error
</PRE></blockquote>

<p> Remove the illegal tracing call.
@@ -116,7 +138,7 @@ all exercises) before continuing. </p>
<blockquote><PRE>
$ java tests.Test
....
Time: 0.076
Time: 0.03

OK (4 tests)
</PRE></blockquote>
@@ -215,20 +237,17 @@ the convention. Make sure your program still passes the JUnit test
your left and right. If they're stuck somewhere, see if you can help
them. </p>

<!-- ============================== -->

<hr />

<h2>2. Dynamic invariants</h2>
<!-- ============================== -->

<br style="page-break-after: always" />
<h2>2. Dynamic invariants</h2>

<h3>a. Check a simple precondition</h3>

<p> <strong>Sample Exercise</strong>: The main point of this exercise
is to make sure your configuration works. We have provided the
answer to this exercise below, so XXX. You need not go through the
thought process of fixing this </p>

<p> <strong>Sample Exercise</strong>: We've provided the answer to
this exercise below to get you started. </p>

<p> <strong>Task:</strong> Pass <code>tests.Test2a</code>.
</p>
@@ -283,7 +302,7 @@ import figures.*;

aspect Answer2a {
before(int newValue): set(int Point.*) &amp;&amp; args(newValue) {
if (newValue < 0) {
if (newValue &lt; 0) {
throw new IllegalArgumentException("too small");
}
}
@@ -322,8 +341,6 @@ an attempt is made to call <code>Group.add()</code> on a
call.
</p>

XXX RENUMBER LATER

<h3>d. Assure input</h3>

<p> <strong>Task: </strong> Pass <code>tests.Test2g</code>.
@@ -380,83 +397,12 @@ throw an <code>IllegalStateException</code> if it is violated. </p>
<p> At this point, check the people to your left and right. If
they're stuck somewhere, see if you can help them. </p>

<!-- ============================== -->

<hr />
<!-- page break -->

<h2>3. Logging</h2>

<h3>d. Check a simple postcondition</h3>

<p> One of the simplest postconditions to check is that a setter
actually sets its value. Write an aspect that throws a
<code>java.lang.RuntimeException</code> if, after calling
<code>setX()</code> on <code>SlothfulPoint</code> objects,
<code>getX()</code> doesn't return the new value. </p>

<p> You'll want to use an <code>args</code> pointcut to expose the
argument to <code>setX()</code> and a <code>target</code> pointcut to
expose the <code>SlothfulPoint</code> object itself (so you can later
call <code>getX()</code> on it).
</p>

<p> An interesting question to think about for discussion is whether
this postcondition should apply when getX() throws an exception, or
when it returns normally, or both? </p>

<p> With this aspect in place, your code should pass
<code>tests.Test2d</code>.
</p>


<h3>e. Check invariant</h3>

<p> There is a method on the <code>Box</code> class, <code>void
checkBoxness()</code>, that checks whether the four points making up a
box are correctly positioned relative to each other (i.e., they form a
rectangle). Write an aspect that will make sure that after every time
the <code>void move(int, int)</code> method on <code>Box</code> is
called, that you also call <code>Box.checkBoxness()</code> to ensure
that the <code>move</code> didn't break this invariant. </p>

<p> With this aspect in place, your code should pass
<code>tests.Test2e</code>.
</p>

<h3>f. Refine your invariant</h3>

<p> <code>move</code> is not the only interesting method on
<code>Box</code>. It may be that a box gets malformed between calls
to <code>move</code>. So instead of checking boxness only
after the <code>move</code> method of <code>Box</code>, check
after the call to every one of <code>Box</code>'s public methods.
</p>

<p> When testing this aspect, you may find yourself facing a
<code>StackOverflowException</code>. If so, carefully look at your
pointcuts. Needless to say, there should not be an infinite loop in
your program. You might want to look at using a <code>within</code>
pointcut for a filter. </p>

<p> (You might even find that this test case aborts with no message,
i.e.,
</p>

<blockquote><pre>
$ java tests.test2f
.
$
</pre></blockquote>

<p> this is a bug in Sun's JVM where a particular stack overflow
causes the VM to abort.)
</p>

<p> Make sure to pass the JUnit test <code>tests.Test2f</code>
before continuing. </p>
<!-- ============================== -->

==================================================
<br style="page-break-after: always" />
<h2>3. Tracing</h2>

<p> The crosscutting feature you will be adding in part (4) will be
support for caching the bound objects of <code>Group</code> figure
@@ -465,7 +411,7 @@ it's useful to explore the system with some tracing aspects. </p>

<h3>a. Simple logging</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test3a</code>.</p>
<p> <strong>Task:</strong> Pass <code>tests.Test3a</code>.</p>

<p> <strong>Tools:</strong> <code>Log.log(String)</code>,
<code>thisJoinPoint.toString()</code>, <code>execution</code>,
@@ -479,7 +425,7 @@ and call <code>Log.log(String)</code></p>

<h3>b. Simple logging</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test3b</code>.</p>
<p> <strong>Task:</strong> Pass <code>tests.Test3b</code>.</p>

<p> <strong>Tools:</strong> <code>target</code>
</p>
@@ -487,7 +433,7 @@ and call <code>Log.log(String)</code></p>

<h3>c. More specialized logging</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test3c</code>.</p>
<p> <strong>Task:</strong> Pass <code>tests.Test3c</code>.</p>

<p> <strong>Tools:</strong>
</p>
@@ -520,7 +466,7 @@ based on the type of a parameter to a method call. </em> </p>

<h3>d. Logging extended to checking an invariant</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test3d</code>.</p>
<p> <strong>Task:</strong> Pass <code>tests.Test3d</code>.</p>

<p> <strong>Tools:</strong> <code>inter-type field declaration</code>
</p>
@@ -530,7 +476,7 @@ based on the type of a parameter to a method call. </em> </p>

<h3>e. Better error messages for 3d</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test3e</code>.</p>
<p> <strong>Task:</strong> Pass <code>tests.Test3e</code>.</p>

<p> <strong>Tools:</strong>
</p>
@@ -581,13 +527,12 @@ previous exercises, you'll be most of the way there. </em> </p>
<p> At this point, check the people to your left and right. If
they're stuck somewhere, see if you can help them. </p>

<hr />

<!-- ============================== -->

<hr />

<!-- page break -->
<h3>4. Caching</h3>
<br style="page-break-after: always" />
<h2>4. Caching</h2>

<p> Computation of the bounding box of <code>Group</code> objects
needs to deal with all aggregate parts of the group, and this
@@ -602,7 +547,7 @@ handle those points contained in Lines and Boxes only if time permits.

<h3>a. Make a constant override</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test4a</code>.</p>
<p> <strong>Task:</strong> Pass <code>tests.Test4a</code>.</p>

<p> <strong>Tools:</strong> <code>around</code>,
<code>FigureElement.MAX_BOUNDS</code>
@@ -623,7 +568,7 @@ around advice intercepting the method.

<h3>b. Make a constant cache</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test4b</code>.
<p> <strong>Task:</strong> Pass <code>tests.Test4b</code>.
</p>

<p> <strong>Tools:</strong> <code>private Rectangle Group.mumble;</code>
@@ -642,7 +587,7 @@ state for every <code>Group</code> object.</em> </p>

<h3>c. Invalidate, part 1</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test4c</code>.
<p> <strong>Task:</strong> Pass <code>tests.Test4c</code>.
</p>

<p> <strong>Tools:</strong> <code>before</code>
@@ -656,7 +601,7 @@ Change your aspect so that it invalidates the cache whenever the

<h3>d. Invalidate, part 2</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test4d</code>.</p>
<p> <strong>Task:</strong> Pass <code>tests.Test4d</code>.</p>

<p> <strong>Tools:</strong> <code>your solution to 3c</code></p>

@@ -670,7 +615,7 @@ where there you cared about method calls. </p>

<h3>e. Invalidate, part 3</h3>

<p> <strong>Problem:</strong> Pass <code>tests.Test4e</code>.</p>
<p> <strong>Task:</strong> Pass <code>tests.Test4e</code>.</p>

<p> <strong>Tools:</strong> <em>You're on you're own</em></p>


Write Preview
Loading…
Cancel
Save