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

Erik Huelsmann ehuels at gmail.com
Fri Jul 15 16:59:00 UTC 2011

Today I was looking at fixing some of our PRINT.* failures in the ansi test

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??


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