Re: [Jython-users] Constructing Java generics in Jython

[Jeff Emanuel <jemanuel@fr...>]

Try something like this to tell Jython to
use a classloader that first looks to the classloader
that loaded your bot before trying its usual
classloader.

   class MyClassLoader extends ClassLoader {
     ClassLoader other;
     MyClassLoader(ClassLoader parent, ClassLoader other) {
       super(parent);
       this.other=other;
     }
     protected Class findClass(String className)
         throws ClassNotFoundException {
       try {
         return super.findClass(className);
       } catch (ClassNotFoundException e) {
         return this.other.findClass(className);
       }
    }
    engineSys.setClassLoader(new 
MyClassLoader(bot.getClass().getClassLoader(),engineSys.getClassLoader()));



Geoff Bache wrote:
> Hi Stefan, Jeff,
>
> I have tried that and it works. Of course it isn't really that useful,
> because I can't just go on defining all my objects in Java or there
> would be no point in using Jython :) One interesting thing is that the
> "isinstance" call in Jython now returns False, so Jython and Java
> clearly have different ideas of what constitutes org.hamcrest.Matcher.
>
> I tried to make PySystemState work, but got into a horrible CLASSPATH
> mess with Eclipse and jython.jar that I haven't yet got my head round.
> In any case, the point of using JSR-223 was to get a generic interface
> for any dynamic language, and importing Jython things directly kind of
> defeats the object there.
>
> Also, it surely shouldn't be necessary? I tried replacing the
> SWTWorkbenchBot with a class that just did this:
>
> import org.hamcrest.Matcher;
>
> public class Method {
>
>     public void doSomething(Matcher matcher) throws Exception {
>         System.out.println(matcher.matches(matcher));
>     }
> }
>
> and then it worked just fine.
>
> Basically, it seems rather like a bug. But I'm still a bit unsure on
> how to investigate it further.
>
> Regards,
> Geoff
>
>
> On Fri, Oct 22, 2010 at 12:58 PM, Stefan Sonnenberg-Carstens
> <stefan.sonnenberg@...> wrote:
>   
>> Or, have you tried this:
>>
>> SWTWorkbenchBot bot = new SWTWorkbenchBot();
>> ScriptEngine engine = new ScriptEngineManager().getEngineByExtension("py");
>> org.hamcrest.Matcher matcher = new org.hamcrest.core.IsAnything();
>> engine.put("bot", bot);
>> engine.put("matcher", matcher);
>> engine.eval("allWidgets = bot.widgets(matcher)");
>>
>> And perhaps, you need to create a PySystemState:
>> http://wiki.python.org/jython/UserGuide#using-jsr-223
>>
>> The classloader lives in sys, so perhaps this solves your issue.
>>
>> Am Fr, 22.10.2010, 10:21 schrieb Geoff Bache:
>>     
>>> Hi Jeff,
>>>
>>>       
>>>> My guess is that there is a classloader mismatch.  Perhaps IsAnything
>>>> and
>>>> its superclasses/interfaces are loaded by one classloader, but those
>>>> accessed
>>>> through the `bot` instance are from another.
>>>>         
>>> I imagine you may be right. Can you give me some hints as to what to
>>> do about it?
>>> Googling "Jython classloader mismatch" didn't find much and I'm pretty new
>>> to
>>> Jython and indeed to Java also.
>>>
>>> I'm using JSR-223, so the "bot" object is created in Java code like this.
>>>
>>> SWTWorkbenchBot bot = new SWTWorkbenchBot();
>>> ScriptEngine engine = new
>>> ScriptEngineManager().getEngineByExtension("py");
>>> engine.put("bot", bot);
>>> engine.eval(reader);
>>>
>>> where "reader" is reading the Python code I sent before. This is a
>>> workaround for
>>> another issue, that the "SWTWorkbenchBot" cannot be constructed in Jython
>>> for
>>> some reason.
>>>
>>> I translated your example code to also do something like this and it
>>> worked fine
>>> though.
>>>
>>> Regards,
>>> Geoff
>>>
>>> ------------------------------------------------------------------------------
>>> Nokia and AT&T present the 2010 Calling All Innovators-North America
>>> contest
>>> Create new apps & games for the Nokia N8 for consumers in  U.S. and Canada
>>> $10 million total in prizes - $4M cash, 500 devices, nearly $6M in
>>> marketing
>>> Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
>>> http://p.sf.net/sfu/nokia-dev2dev
>>> _______________________________________________
>>> Jython-users mailing list
>>> Jython-users@...
>>> https://lists.sourceforge.net/lists/listinfo/jython-users
>>>
>>>
>>>       
>> --
>> MfG,
>>
>> Stefan Sonnenberg-Carstens
>>
>> IT Architect
>> - Project management
>> - System analysis, design and build
>> - Security and business continuity
>> - IT risk management
>>
>>     
>
> ------------------------------------------------------------------------------
> Nokia and AT&T present the 2010 Calling All Innovators-North America contest
> Create new apps & games for the Nokia N8 for consumers in  U.S. and Canada
> $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing
> Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store 
> http://p.sf.net/sfu/nokia-dev2dev
> _______________________________________________
> Jython-users mailing list
> Jython-users@...
> https://lists.sourceforge.net/lists/listinfo/jython-users
>   

Re: [Jython-users] Constructing Java generics in Jython

[Stefan Behnel <stefan_ml@be...>]

Geoff Bache, 21.10.2010 14:49:
> I'm currently trying to make SWTBot, a tool for testing Java SWT GUIs,
> work from Jython.
> (See https://bugs.eclipse.org/bugs/show_bug.cgi?id=328342 for more details)
>
> I ran into a bit of an issue with a Java Generic

Note that generics are a pure compile time thing in Java. There is no 
runtime type checking of parametrised types in the JVM, and they are only 
barely introspectable. So there isn't really much interference with Jython.

Stefan

Re: [Jython-users] Constructing Java generics in Jython

[Geoff Bache <geoff.bache@gm...>]

Hi Stefan, Jeff,

I have tried that and it works. Of course it isn't really that useful,
because I can't just go on defining all my objects in Java or there
would be no point in using Jython :) One interesting thing is that the
"isinstance" call in Jython now returns False, so Jython and Java
clearly have different ideas of what constitutes org.hamcrest.Matcher.

I tried to make PySystemState work, but got into a horrible CLASSPATH
mess with Eclipse and jython.jar that I haven't yet got my head round.
In any case, the point of using JSR-223 was to get a generic interface
for any dynamic language, and importing Jython things directly kind of
defeats the object there.

Also, it surely shouldn't be necessary? I tried replacing the
SWTWorkbenchBot with a class that just did this:

import org.hamcrest.Matcher;

public class Method {

    public void doSomething(Matcher matcher) throws Exception {
        System.out.println(matcher.matches(matcher));
    }
}

and then it worked just fine.

Basically, it seems rather like a bug. But I'm still a bit unsure on
how to investigate it further.

Regards,
Geoff


On Fri, Oct 22, 2010 at 12:58 PM, Stefan Sonnenberg-Carstens
<stefan.sonnenberg@...> wrote:
> Or, have you tried this:
>
> SWTWorkbenchBot bot = new SWTWorkbenchBot();
> ScriptEngine engine = new ScriptEngineManager().getEngineByExtension("py");
> org.hamcrest.Matcher matcher = new org.hamcrest.core.IsAnything();
> engine.put("bot", bot);
> engine.put("matcher", matcher);
> engine.eval("allWidgets = bot.widgets(matcher)");
>
> And perhaps, you need to create a PySystemState:
> http://wiki.python.org/jython/UserGuide#using-jsr-223
>
> The classloader lives in sys, so perhaps this solves your issue.
>
> Am Fr, 22.10.2010, 10:21 schrieb Geoff Bache:
>> Hi Jeff,
>>
>>> My guess is that there is a classloader mismatch.  Perhaps IsAnything
>>> and
>>> its superclasses/interfaces are loaded by one classloader, but those
>>> accessed
>>> through the `bot` instance are from another.
>>
>> I imagine you may be right. Can you give me some hints as to what to
>> do about it?
>> Googling "Jython classloader mismatch" didn't find much and I'm pretty new
>> to
>> Jython and indeed to Java also.
>>
>> I'm using JSR-223, so the "bot" object is created in Java code like this.
>>
>> SWTWorkbenchBot bot = new SWTWorkbenchBot();
>> ScriptEngine engine = new
>> ScriptEngineManager().getEngineByExtension("py");
>> engine.put("bot", bot);
>> engine.eval(reader);
>>
>> where "reader" is reading the Python code I sent before. This is a
>> workaround for
>> another issue, that the "SWTWorkbenchBot" cannot be constructed in Jython
>> for
>> some reason.
>>
>> I translated your example code to also do something like this and it
>> worked fine
>> though.
>>
>> Regards,
>> Geoff
>>
>> ------------------------------------------------------------------------------
>> Nokia and AT&T present the 2010 Calling All Innovators-North America
>> contest
>> Create new apps & games for the Nokia N8 for consumers in  U.S. and Canada
>> $10 million total in prizes - $4M cash, 500 devices, nearly $6M in
>> marketing
>> Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
>> http://p.sf.net/sfu/nokia-dev2dev
>> _______________________________________________
>> Jython-users mailing list
>> Jython-users@...
>> https://lists.sourceforge.net/lists/listinfo/jython-users
>>
>>
>
>
> --
> MfG,
>
> Stefan Sonnenberg-Carstens
>
> IT Architect
> - Project management
> - System analysis, design and build
> - Security and business continuity
> - IT risk management
>

Re: [Jython-users] Constructing Java generics in Jython

[Stefan Sonnenberg-Carstens <stefan.sonnenberg@py...>]

Or, have you tried this:

SWTWorkbenchBot bot = new SWTWorkbenchBot();
ScriptEngine engine = new ScriptEngineManager().getEngineByExtension("py");
org.hamcrest.Matcher matcher = new org.hamcrest.core.IsAnything();
engine.put("bot", bot);
engine.put("matcher", matcher);
engine.eval("allWidgets = bot.widgets(matcher)");

And perhaps, you need to create a PySystemState:
http://wiki.python.org/jython/UserGuide#using-jsr-223

The classloader lives in sys, so perhaps this solves your issue.

Am Fr, 22.10.2010, 10:21 schrieb Geoff Bache:
> Hi Jeff,
>
>> My guess is that there is a classloader mismatch.  Perhaps IsAnything
>> and
>> its superclasses/interfaces are loaded by one classloader, but those
>> accessed
>> through the `bot` instance are from another.
>
> I imagine you may be right. Can you give me some hints as to what to
> do about it?
> Googling "Jython classloader mismatch" didn't find much and I'm pretty new
> to
> Jython and indeed to Java also.
>
> I'm using JSR-223, so the "bot" object is created in Java code like this.
>
> SWTWorkbenchBot bot = new SWTWorkbenchBot();
> ScriptEngine engine = new
> ScriptEngineManager().getEngineByExtension("py");
> engine.put("bot", bot);
> engine.eval(reader);
>
> where "reader" is reading the Python code I sent before. This is a
> workaround for
> another issue, that the "SWTWorkbenchBot" cannot be constructed in Jython
> for
> some reason.
>
> I translated your example code to also do something like this and it
> worked fine
> though.
>
> Regards,
> Geoff
>
> ------------------------------------------------------------------------------
> Nokia and AT&T present the 2010 Calling All Innovators-North America
> contest
> Create new apps & games for the Nokia N8 for consumers in  U.S. and Canada
> $10 million total in prizes - $4M cash, 500 devices, nearly $6M in
> marketing
> Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
> http://p.sf.net/sfu/nokia-dev2dev
> _______________________________________________
> Jython-users mailing list
> Jython-users@...
> https://lists.sourceforge.net/lists/listinfo/jython-users
>
>


-- 
MfG,

Stefan Sonnenberg-Carstens

IT Architect
- Project management
- System analysis, design and build
- Security and business continuity
- IT risk management

Re: [Jython-users] Constructing Java generics in Jython

[Stefan Sonnenberg-Carstens <stefan.sonnenberg@py...>]

So your program looks basically like this:

SWTWorkbenchBot bot = new SWTWorkbenchBot();
ScriptEngine engine = new ScriptEngineManager().getEngineByExtension("py");
engine.put("bot", bot);
engine.eval(StringReader("matcher = org.hamcrest.core.IsAnything()\n print
isinstance(matcher, org.hamcrest.Matcher)\n allWidgets =
bot.widgets(matcher)"));

Perhaps you could for once try without the Reader object:

SWTWorkbenchBot bot = new SWTWorkbenchBot();
ScriptEngine engine = new ScriptEngineManager().getEngineByExtension("py");
engine.put("bot", bot);
engine.eval("matcher = org.hamcrest.core.IsAnything()\n print
isinstance(matcher, org.hamcrest.Matcher)\n allWidgets =
bot.widgets(matcher)");


Am Fr, 22.10.2010, 10:21 schrieb Geoff Bache:
> Hi Jeff,
>
>> My guess is that there is a classloader mismatch.  Perhaps IsAnything
>> and
>> its superclasses/interfaces are loaded by one classloader, but those
>> accessed
>> through the `bot` instance are from another.
>
> I imagine you may be right. Can you give me some hints as to what to
> do about it?
> Googling "Jython classloader mismatch" didn't find much and I'm pretty new
> to
> Jython and indeed to Java also.
>
> I'm using JSR-223, so the "bot" object is created in Java code like this.
>
> SWTWorkbenchBot bot = new SWTWorkbenchBot();
> ScriptEngine engine = new
> ScriptEngineManager().getEngineByExtension("py");
> engine.put("bot", bot);
> engine.eval(reader);
>
> where "reader" is reading the Python code I sent before. This is a
> workaround for
> another issue, that the "SWTWorkbenchBot" cannot be constructed in Jython
> for
> some reason.
>
> I translated your example code to also do something like this and it
> worked fine
> though.
>
> Regards,
> Geoff
>
> ------------------------------------------------------------------------------
> Nokia and AT&T present the 2010 Calling All Innovators-North America
> contest
> Create new apps & games for the Nokia N8 for consumers in  U.S. and Canada
> $10 million total in prizes - $4M cash, 500 devices, nearly $6M in
> marketing
> Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
> http://p.sf.net/sfu/nokia-dev2dev
> _______________________________________________
> Jython-users mailing list
> Jython-users@...
> https://lists.sourceforge.net/lists/listinfo/jython-users
>
>


-- 
MfG,

Stefan Sonnenberg-Carstens

Re: [Jython-users] Constructing Java generics in Jython

[Geoff Bache <geoff.bache@gm...>]

Hi Jeff,

> My guess is that there is a classloader mismatch.  Perhaps IsAnything and
> its superclasses/interfaces are loaded by one classloader, but those
> accessed
> through the `bot` instance are from another.

I imagine you may be right. Can you give me some hints as to what to
do about it?
Googling "Jython classloader mismatch" didn't find much and I'm pretty new to
Jython and indeed to Java also.

I'm using JSR-223, so the "bot" object is created in Java code like this.

SWTWorkbenchBot bot = new SWTWorkbenchBot();
ScriptEngine engine = new ScriptEngineManager().getEngineByExtension("py");
engine.put("bot", bot);
engine.eval(reader);

where "reader" is reading the Python code I sent before. This is a
workaround for
another issue, that the "SWTWorkbenchBot" cannot be constructed in Jython for
some reason.

I translated your example code to also do something like this and it
worked fine
though.

Regards,
Geoff