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Diffstat (limited to 'docs/progGuideDB/implementation.xml')
| -rw-r--r-- | docs/progGuideDB/implementation.xml | 92 |
1 files changed, 46 insertions, 46 deletions
diff --git a/docs/progGuideDB/implementation.xml b/docs/progGuideDB/implementation.xml index 52da14d9c..e1fa05f2b 100644 --- a/docs/progGuideDB/implementation.xml +++ b/docs/progGuideDB/implementation.xml @@ -5,7 +5,7 @@ <sect1> <title>Compiler Notes</title> - <para> + <para> The initial implementations of AspectJ have all been compiler-based implementations. Certain elements of AspectJ's semantics are difficult to implement without making modifications @@ -25,7 +25,7 @@ </para> <programlisting><![CDATA[ - before(): get(int Point.x) { System.out.println("got x"); } +before(): get(int Point.x) { System.out.println("got x"); } ]]></programlisting> <para> @@ -36,7 +36,7 @@ compiled, whether changes were made later, etc. </para> - <para> + <para> But AspectJ implementations are permitted to deviate from this in a well-defined way -- they are permitted to advise only accesses in <emphasis>code the implementation controls</emphasis>. Each @@ -67,11 +67,11 @@ can be advised only if ajc controls the bytecode for the method or constructor body in question. The end of an exception handler is underdetermined in bytecode, - so ajc will not implement after or around advice on handler join + so ajc will not implement after or around advice on handler join points. - Similarly, ajc cannot implement around advice on initialization - or preinitialization join points. - In cases where ajc cannot implement advice, it will emit a + Similarly, ajc cannot implement around advice on initialization + or preinitialization join points. + In cases where ajc cannot implement advice, it will emit a compile-time error noting this as a compiler limitation. </para> @@ -100,35 +100,35 @@ </para> <para> When declaring members on interfaces, the implementation must - control both the interface and the top-level implementors of + control both the interface and the top-level implementors of that interface (the classes that implement the interface but do not have a superclass that implements the interface). You may weave these separately, but be aware that you will get runtime exceptions if you run the affected top-level classes - without the interface as produced by the same ajc implementation. - Any intertype declaration of an abstract method on an interface - must be specified as public, you will get a compile time error - message indicating this is a compiler limitation if you do not + without the interface as produced by the same ajc implementation. + Any intertype declaration of an abstract method on an interface + must be specified as public, you will get a compile time error + message indicating this is a compiler limitation if you do not specify public. A non-abstract method declared on an interface can use any access modifier except protected. Note that this is - different to normal Java rules where all members declared in + different to normal Java rules where all members declared in an interface are implicitly public. - Finally, note that one cannot define static fields or methods + Finally, note that one cannot define static fields or methods on interfaces. </para> <para> - When declaring methods on target types, only methods declared - public are recognizable in the bytecode, so methods must be - declared public to be overridden in any subtype or to be called + When declaring methods on target types, only methods declared + public are recognizable in the bytecode, so methods must be + declared public to be overridden in any subtype or to be called from code in a later compile using the target type as a library. </para> - + <para> Other AspectJ implementations, indeed, future versions of ajc, may define <emphasis>code the implementation controls</emphasis> more liberally or restrictively, so long as they comport with the Java language. For example, the <literal>call</literal> pointcut does - not pick out reflective calls to a method implemented in + not pick out reflective calls to a method implemented in <literal>java.lang.reflect.Method.invoke(Object, Object[])</literal>. Some suggest that the call "happens" and the call pointcut should pick it out, but the AspectJ language shouldn't anticipate what happens @@ -172,12 +172,12 @@ </para> <programlisting><![CDATA[ - class Test { - void main(String[] args) { - System.out.println(Test.class); // calls Class.forName - System.out.println(args[0] + args[1]); // calls StringBuffer.append - } - } +class Test { + void main(String[] args) { + System.out.println(Test.class); // calls Class.forName + System.out.println(args[0] + args[1]); // calls StringBuffer.append + } +} ]]></programlisting> <para>In short, the join point model of the current AspectJ @@ -217,7 +217,7 @@ </para> <programlisting><![CDATA[ - cflow(call(void foo()) || handler(java.io.IOException)) +cflow(call(void foo()) || handler(java.io.IOException)) ]]></programlisting> <para> will capture all join points in the control flow of a call to @@ -236,9 +236,9 @@ </para> <programlisting><![CDATA[ - before(): handler(java.io.IOException) && cflow(void parse()) { - System.out.println("about to handle an exception while parsing"); - } +before(): handler(java.io.IOException) && cflow(void parse()) { + System.out.println("about to handle an exception while parsing"); +} ]]></programlisting> <para> @@ -258,16 +258,16 @@ </para> <programlisting><![CDATA[ - class C { - double d = Math.sqrt(2); - } +class C { + double d = Math.sqrt(2); +} ]]></programlisting> <para> are considered part of constructors by the time AspectJ gets ahold of bytecode. That is, the assignment of d to the square root of two happens <emphasis>inside</emphasis> the default constructor of - C. + C. </para> <para> @@ -280,15 +280,15 @@ </para> <programlisting><![CDATA[ - aspect A { - C.new(Object o) {} // implicitly calls super() +aspect A { + C.new(Object o) {} // implicitly calls super() - public static void main(String[] args) { - System.out.println((new C() ).d); // prints 1.414... - System.out.println((new C(null)).d); // prints 0.0 - } + public static void main(String[] args) { + System.out.println((new C() ).d); // prints 1.414... + System.out.println((new C(null)).d); // prints 0.0 +} ]]></programlisting> - + <para> It is the job of an inter-type constructor to do all the required initialization, or to delegate to a <literal>this</literal> @@ -302,8 +302,8 @@ <para>Writing aspects in annotation-style is subject to the same bytecode limitations since the binary aspects take the same form and are woven in the same way. However, the implementation - differences (e.g., the mechanism for implementing around advice) - may be apparent at runtime. See the documentation on annotation-style + differences (e.g., the mechanism for implementing around advice) + may be apparent at runtime. See the documentation on annotation-style for more information. </para> </sect1> @@ -311,7 +311,7 @@ <title>Summary of implementation requirements</title> <para> This summarizes the requirements of our implementation of AspectJ. - For more details, see the relevant sections of this guide. + For more details, see the relevant sections of this guide. </para> <itemizedlist spacing="compact"> <listitem> @@ -343,7 +343,7 @@ <para>Implementation Caveats</para> <itemizedlist spacing="compact"> <listitem> - <para>The initialization and preinitialization join points + <para>The initialization and preinitialization join points do not support around advice</para> </listitem> <listitem> @@ -355,7 +355,7 @@ </itemizedlist> </listitem> <listitem> - <para>Declaring members on an interface in an aspect affects only + <para>Declaring members on an interface in an aspect affects only the topmost implementing classes the implementation controls.</para> </listitem> <listitem> @@ -363,7 +363,7 @@ </listitem> <listitem> <para> - Runtime <literal>ClassCastException</literal> may result + Runtime <literal>ClassCastException</literal> may result from supplying a supertype of the actual type as an argument to proceed(..) in around advice.</para> </listitem> |