Jython

http://jsug.at/wiki/Meeting_49

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Jython
PythonontheJVM
RobertBachmann
JSUGMeeting#49
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2. Outline
•UseCases
•Limitations
•Usage&javax.script/JSR223
•A(short)casestudy
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3. Python?
•Scriptinglanguage
•Dynamicallytyped
•Standardinterpreter: (C)Python
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4. A broader view…
•JRuby(RubyontheJVM)
•Groovy(nativeJVMlanguage)
•CLR:IronPython&IronRuby
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5. Use cases
•Re-useofJavalibraries
•Re-useofJavainfrastructure
•AddingscriptingabilitiestoaJavasoftware
•Prototyping
•Testscripting
•Performanceimprovementsw.r.t(C)Python
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6. Limitations
•NotaJavareplacement(cf. Scala)
•Nocurrentcompiler
•CannotusePythonmoduleswithCcode
•Jythonlagsbehind(C)Python&IronPython
IJython: 2.5.3stable/2.7a2alpha
I(C)Python: 2.7stable
IIronPython: 2.7stable
•PerformanceworsethanJava
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7. Usage
•“HelloWorld”withJython
•UsingJavafromJython
•UsingJythonwithjavax.script
•UsingJythonfromJava
•Deploymentoptions
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8. Hello World
# program.py
print”Hello␣World”
$ jython program.py
Hello World
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9. Hello World with classes and modules
### demo.py
classHello:
defgreet(self, name):
print”Hello␣”+ name
### program.py
fromdemoimportHello
h = Hello()
h.greet(”JSUG”)
# or:
importdemo
h = demo.Hello()
h.greet(”JSUG”)
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10. Using Java from Jython – Example
# Hello World with Swing
fromjavax.swingimportJOptionPane
JOptionPane.showMessageDialog(None, ”Hello!”)
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11. Using Java from Jython – Notes
•Jythonclassescan
IimplementJavainterfaces
IextendJavaclasses
•Classpath
Iimportusesclasspathviasys.path
IAddJARsviasys.path.append()
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12. javax.script
•JSR223: ScriptingfortheJavaTMPlatform
•APIforusingscriptinglanguageswithJava
•Centralclass: ScriptEngine
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13. javax.script
ScriptEngineManager factory =
newScriptEngineManager();
ScriptEngine engine =
factory.getEngineByName( ”python”);
engine.eval(”print␣’Hello,␣World’”);
engine.put(”x”, 10)
engine.eval(”y␣=␣x␣*␣2”);
Object y = engine.get( ”y”)
System.out.println(y)
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14. Using Jython classes from Java
•Steps:
IDerivefromJavaclass/interface
IUseJythonInterpertertocreatean
instance
ICalltheinstance’s__tojava__method
•Completesolution:
http://www.jython.org/jythonbook/en/1.0/
JythonAndJavaIntegration.html
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15. Deployment options
•ServletContaier
Iorg.python.util.PyServlet
IWSGIviamodjy
•Standalone.jar
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16. Case study
•Scenario: AClibrarywithJavaand.Net
wrappers
•Challenge: Automatedtestingofalllibraries
•Solution: Single-sourcetestautomation
withJython/IronPython
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17. Questions?
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18. Thanks
Twitter@robertbachmann
Emailrb@ — .at
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