[armedbear-devel] Fixing PRINT.RANDOM-STATE.1

[Mark Evenson]

I think all you need to serialize is a structure that contains the long seed for java.until.Random.  Or am I missing something?

Sent from my iPad

On Jul 15, 2011, at 6:59 PM, Erik Huelsmann <ehuels at gmail.com> wrote:

> 
> Today I was looking at fixing some of our PRINT.* failures in the ansi test suite.
> 
> Hoping to get an easy start, I started looking PRINT.RANDOM-STATE.1 The problem shown by the test is that our RANDOM-STATEs are not printable. From the perspective of ABCL, that's logical: Java's Random objects are serializable, but as everywhere in Java, it's serialization is internal to the implementation. The Random object is initialized using a 'seed' long value, but there's no way to extract a 'seed' value from the object to be used to initialize an object into the same state.
> 
> So, I'm now pondering what action to take. I'm seeing several options:
> 
> 1. build our own pseudo random number generator with its own random state
> 2. serialize the Random object to a byte array and use that array as some sort of printed representation (sure, we'll definitely need to look into ways to load)
> 
> The advantage of (1) is that we can create it all in Lisp, however, it's  pure additional code, since we won't be leveraging what's already there.
> 
> The advantage of (2) is that we can use what Java maintains for us and even better: we can use the random number generator shared between Lisp and Java code. I imagine the disadvantage of this solution is that the serialization of the random state can differ between Java versions and implementations.
> 
> Any ideas??
> 
> 
> Bye,
> 
> 
> Erik.
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