Re: [Jython-users] Strange behavior of Integer and Double

[Ben H. <be...@in...>]

Finn Bock wrote:

> [Will]
> >I have run into some surprising behavior of Java Integer objects while using
> >jython:
> <example snipped>
> >What am I doing wrong?  How can I keep Integer and Double objects from being
> >converted to Java primitives?
>
> You can't. The eagerness with which Jython converts the java.lang.*
> wrapper classes to instances of native python classes have been
> discussed previousely:
>
> http://mail.python.org/pipermail/jpython-interest/1999-December/002590.html

My main concern is: will this obstruct the use of Java APIs which require Boolean
parameters? In the example William gives the expected method is not invoked. Will
developers using Jython to script or integrate existing Java systems encounter
problems; either hard to find bugs, or method signatures that cant be invoked?

> It is basicly the same problem you have re-discovered. I'm still not
> convinved that it is a net win to reduce this eagerness.
>
> http://mail.python.org/pipermail/jpython-interest/1999-December/002596.html

From the above article, Finn Bock wrote:

     One of the downsides of this patch, is that the simple if statement
     below will no longer work. I am afraid to think about the
     incompabilities this change will introduce in existing jpython
     programs.

     if not lang.Boolean.FALSE:
        print "FALSE"

Equivalently, the statement below is not legal Java. Is there need to support
semantics that arent in Java? I cant imagine many developers using expressions
similar to above, since they couldnt in Java anyway.

     if (! Boolean.FALSE) {}

As I understand the issues, I *think* I prefer a less eager conversion policy,
but would be happy to hear more counter-arguments.

Regards
Ben

--
Ben Hutchison
Software Engineer-Market Predictor
Webmind Australia
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