1.1 --- a/docs/index.html Fri Jan 21 18:22:18 2005 +0100
1.2 +++ b/docs/index.html Fri Jan 21 18:22:28 2005 +0100
1.3 @@ -1,29 +1,37 @@
1.4 <?xml version="1.0" encoding="iso-8859-1"?>
1.5 <html xmlns="http://www.w3.org/1999/xhtml">
1.6 <head>
1.7 - <title>ClassFile</title>
1.8 + <title>javaclass/ClassFile</title>
1.9 <meta name="generator" content="amaya 8.1a, see http://www.w3.org/Amaya/" />
1.10 <link xmlns:xlink="http://www.w3.org/1999/xlink" href="styles.css"
1.11 rel="stylesheet" type="text/css" />
1.12 </head>
1.13
1.14 <body>
1.15 -<h1>ClassFile</h1>
1.16 +<h1>javaclass</h1>
1.17 +
1.18 +<p>The javaclass collection of packages and utilities (also known as
1.19 +ClassFile) provides a means of importing Java classes and packages directly
1.20 +into Python, without the need for a Java virtual machine, so that the classes
1.21 +may be instantiated, accessed, run and manipulated just like Python classes,
1.22 +and that the resulting objects and methods can be accessed and manipulated
1.23 +just like Python objects and methods.</p>
1.24
1.25 -<p>The ClassFile collection of packages and utilities provides a means of
1.26 -importing Java classes and packages directly into Python, without the need
1.27 -for a Java virtual machine, so that the classes may be instantiated,
1.28 -accessed, run and manipulated just like Python classes, and that the
1.29 -resulting objects and methods can be accessed and manipulated just like
1.30 -Python objects and methods.</p>
1.31 +<h2>Quick Examples</h2>
1.32 +
1.33 +<p>It can be quicker to see what this is about by seeing some examples.</p>
1.34
1.35 -<h2>Quick Example</h2>
1.36 +<h3>The Not Very Convincing Example</h3>
1.37 +
1.38 +<p>You can run Java classes by finding one with a main method and executing
1.39 +it. Here's a comparison of a freshly prepared Java class being run in Python
1.40 +and in a Java virtual machine:</p>
1.41
1.42 <p class="prompt">cd tests/</p>
1.43
1.44 <p class="prompt">javac Value.java</p>
1.45
1.46 -<p class="prompt">../runclass.py Value</p>
1.47 +<p class="prompt">runclass.py Value</p>
1.48
1.49 <p class="result">v.getValue() correct: 123<br />
1.50 v.getValue() correct: 456<br />
1.51 @@ -49,6 +57,46 @@
1.52 v2.add(-123) correct: 0<br />
1.53 v2.getValue() correct: 255</p>
1.54
1.55 +<h3>The Slightly More Credible Example</h3>
1.56 +
1.57 +<p>It can be more interesting to get into Python's interactive mode and then
1.58 +start playing around with Java classes:</p>
1.59 +
1.60 +<p class="python-result">Python 2.2.2 (#2, Jan 21 2005, 16:16:57)<br />
1.61 +[GCC 2.96 20000731 (Red Hat Linux 7.3 2.96-112)] on linux2<br />
1.62 +Type "help", "copyright", "credits" or "license" for more information.</p>
1.63 +
1.64 +<p class="python-prompt">import javaclass.classhook</p>
1.65 +
1.66 +<p class="python-prompt">from __this__ import Value</p>
1.67 +
1.68 +<p class="python-prompt">dir()</p>
1.69 +
1.70 +<p class="python-result">['Value', '__builtins__', '__doc__', '__name__',
1.71 +'javaclass']</p>
1.72 +
1.73 +<p class="python-prompt">dir(Value)</p>
1.74 +
1.75 +<p class="python-result">['__class__', '__delattr__', '__dict__', '__doc__',
1.76 +'__getattribute__', '__hash__', '__init__', '__init______I_', '__module__',
1.77 +'__new__', '__reduce__', '__repr__', '__setattr__', '__str__', '__weakref__',
1.78 +'add', 'add____I_', 'compare', 'compare____I_', 'getClass', 'getClass___',
1.79 +'getValue', 'getValue___', 'isPositive', 'isPositive___', 'main',
1.80 +'main___java__lang__String_array_', 'newValue', 'newValue___', 'setValue',
1.81 +'setValue____I_']</p>
1.82 +
1.83 +<p class="python-prompt">v = Value(20050121)</p>
1.84 +
1.85 +<p class="python-prompt">v.getValue()</p>
1.86 +
1.87 +<p class="python-result">20050121</p>
1.88 +
1.89 +<p class="python-prompt">v.setValue(20050401)</p>
1.90 +
1.91 +<p class="python-prompt">v.getValue()</p>
1.92 +
1.93 +<p class="python-result">20050401</p>
1.94 +
1.95 <h2>Motivation</h2>
1.96
1.97 <p>Pick one of the following:</p>
1.98 @@ -62,6 +110,26 @@
1.99 bytecode on.</li>
1.100 <li>Experimentation around import hooks, bytecode generation; observation
1.101 of different runtime and type systems interacting.</li>
1.102 + <li>Using Python libraries from Java.</li>
1.103 +</ul>
1.104 +
1.105 +<h2>Limitations</h2>
1.106 +
1.107 +<p>It isn't all great, however. Here are some reasons why this might not do
1.108 +what you want it to:</p>
1.109 +<ul>
1.110 + <li>It runs on the Python runtime which does not have the security,
1.111 + threading and just-in-time compiler features that people enjoy about Java
1.112 + runtimes, so if what you like to do is to run one big servlet container
1.113 + with lots of classes and threads from different people floating around,
1.114 + this isn't going to protect them from doing all sorts of things to each
1.115 + other and to your system. However, you may take the unfashionable view
1.116 + that the operating system is supposed to do that kind of thing.</li>
1.117 + <li>It works by generating Python bytecode from the Java bytecode in class
1.118 + files (and .jar archives). Generally, anyone who is anyone in the Python
1.119 + pantheon has largely recommended against doing anything with the
1.120 + bytecode, despite noble efforts to make exciting things happen by
1.121 + transforming it, optimising it, and so on - </li>
1.122 </ul>
1.123 </body>
1.124 </html>
