Java is killing me! (AKA: Java for Pythonheads?)

Billy Earney billy.earney at gmail.com
Fri Aug 12 19:44:16 CEST 2011


Look into jython.  You might be able to run your python code, directly in
java. :)

http://www.jython.org/


On Fri, Aug 12, 2011 at 12:02 PM, kj <no.email at please.post> wrote:

>
>
>
> *Please* forgive me for asking a Java question in a Python forum.
> My only excuse for this no-no is that a Python forum is more likely
> than a Java one to have among its readers those who have had to
> deal with the same problems I'm wrestling with.
>
> Due to my job, I have to port some Python code to Java, and write
> tests for the ported code.  (Yes, I've considered finding myself
> another job, but this is not an option in the immediate future.)
>
> What's giving me the hardest time is that the original Python code
> uses a lot of functions with optional arguments (as is natural to
> do in Python).
>
> As far as I can tell (admittedly I'm no Java expert, and have not
> programmed in it since 2001), to implement a Java method with n
> optional arguments, one needs at least 2**n method definitions.
> Even if all but one of these definitions are simple wrappers that
> call the one that does all the work, it's still a lot of code to
> wade through, for nothing.
>
> That's bad enough, but even worse is writing the unit tests for
> the resulting mountain of fluffCode.  I find myself writing test
> classes whose constructors also require 2**n definitions, one for
> each form of the function to be tested...
>
> I ask myself, how does the journeyman Python programmer cope with
> such nonsense?
>
> For the sake of concreteness, consider the following run-of-the-mill
> Python function of 3 arguments (the first argument, xs, is expected
> to be either a float or a sequence of floats; the second and third
> arguments, an int and a float, are optional):
>
>   def quant(xs, nlevels=MAXN, xlim=MAXX):
>        if not hasattr(xs, '__iter__'):
>            return spam((xs,), n, xlim)[0]
>
>        if _bad_quant_args(xs, nlevels, xlim):
>            raise TypeError("invalid arguments")
>
>        retval = []
>        for x in xs:
>            # ...
>            # elaborate acrobatics that set y
>            # ...
>            retval.append(y)
>
>        return retval
>
> My Java implementation of it already requires at least 8 method
> definitions, with signatures:
>
>    short[] quant (float[], int    , float)
>    short[] quant (float[], int           )
>    short[] quant (float[],          float)
>    short[] quant (float[]                )
>
>    short   quant (float  , int    , float)
>    short   quant (float  , int           )
>    short   quant (float  ,          float)
>    short   quant (float                  )
>
> Actually, for additional reasons, too arcane to go into, I also
> need four more:
>
>    short   quant (Float  , Integer, Float)
>    short   quant (Float  , Integer       )
>    short   quant (Float  ,          Float)
>    short   quant (Float                  )
>
> Writing JUnit tests for these methods is literally driving me
> INSANE.
>
> Some advice on implementing and testing functions with optional
> arguments in Java would be appreciated.
>
> TIA!
>
> kj
> --
> http://mail.python.org/mailman/listinfo/python-list
>
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