Re: [Jython-dev] Jython and native java merged with simplicity

[Samuele P. <pe...@in...>]

Hi, I found your mail a bit confusing, maybe there was just too
much meta comments <wink>.

I see three different points:
- jython is slow vs. java
- subclassing a PyObject subclass from jython have problem with mutability of
the instances of the resulting class
  This should be solved, probably in 2.2, given that to have a jython 2.2 we
should somehow implement the descr changes
  happened to CPython
- a way to solve (partially) both the above problems, although in my opinion
they are unrelated.

In any case adding new keywords and strange semantics is a no-go.

Although I have maybe understood what was the idea behind your words, I don't
want to try to re-explain it confusing
things further, so please please restate it more clearly...

in any case this is an open source projects, prosal and patches are always
welcome.

Samuele Pedroni.



----- Original Message -----
From: john coppola <joh...@ya...>
To: <jyt...@li...>
Sent: Tuesday, August 07, 2001 2:03 AM
Subject: [Jython-dev] Jython and native java merged with simplicity


> After examining the Jython JAPI, it is quite clear
> that the internal operation of the Interpreter is
> quite different.  The jAPI of Jython leverages java's
> object oriented nature to implement a Python
> equivalent in  java.  The jython API has some
> interesting features but has some flaws as well.  I
> would like to see these things changed in future
> releases of Jython:
>
> It is very easy to create a true Python class in Java
> using the Jython Api.  But, there is, as usual a
> better way to go about things which would make things
> run much faster and with greater flexibility.
>
> Now, one could create a true Python class in java, but
> the performance boost is minimal and not worth the
> time.
>
> Native java code runs much faster.  Proof of this is
> the cPickle module implementation in java.  The speed
> of "jPickle" is the same speed as cPickle.
>
> Here is a code comparison for a simple program:
> from time import time
> def test():
>     start = time()
>     total = 0.0
>     for i in range(0,1000000):
>         total = total + i + i*2.0
>     print time()- start
>
> This test on my computer:
>   python2.0:                     2.77 seconds
>   jython2.1a1:                   7.40 seconds
>   native java:                   0.014 seconds
>
> 197 times faster than Python
> 528 times faster than Jython
>
> It would be nice if a python class could leverage the
> speed of java, while having the flexibility of Python.
> We should in theory be able to do this using a Mix-In
> approach.
>
> public class jSpam implements PyObject {
>     public pyOb = new PyObject();
>
>     public void setOb(PyObject ob) {
>         pyOb = ob;
>     }
> }
>
>
> import jSpam # true java class
> class Dummy: pass
>
> Class Foo(Dummy,jSpam):
>     def __init__(self,name):
>         self.name=name
>
> Now, in theory this code should work:
>
> foo=Foo("foo")
>
> This code bombs because inhereting from jSpam has
> interfered with our inheritence from Dummy.
>
> The reason it bombs is because we cannot set
> attributes on the java class we inherited from.  This
> makes sense since java is statically typed. We should
> be able to set attributes on the Foo portion of the
> object.  Jython does not understand this.
>
>
> We really need to include a feature in Jython that can
> leverage Java's speed with a simple api layer to do
> so.
> For lack of better terminology I'll call it a ghosting
> and skeletons.
>
> Ghosting is the layer in that will provide hooks into
> python types mapped into java skeleton classes. So
> everytime we change a python attribute, the attribute
> is updated in the java skeleton automatically.  This
> will in effect pin the Python class to a java class
> removing some of the dynamic flexibility we have with
> the python classes, but the speed gain is tremendous,
> so worth our while.
>
> so in java maybe we have:
>
>    public class mySkeleton implements ghosting
>
> the Ghosting interface are the hooks needed by Jython
> to map a Python object to it's skeleton in java
>
> perhaps syntax in Jython would look like:
>    from spam import Spam with jSpam skeleton
>
>    This would import Spam from the spam module and
>    associate the Spam class with the jSpam skeleton.
>
> Alternate syntax may look like:
>    from spam import Spam with jSpam skeleton as Spam1
>    from spam import Spam with jSpam2 skeleton as Spam2
>
> Where Spam1 and Spam2 have been linked with different
> java skeletons.
>
> A system such as this would provide an easy way to
> utilize java's speed and enable Jython to run several
> times faster than cPython where computationally
> intensive algorithms could be done in the native java
> skeleton class.
>
> John Coppola
>
>
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