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Re: [Jython-users] Overloaded Java method handing changes between 2.7.2 and 2.7.3?
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From: Adam B. <ada...@gm...> - 2024-06-07 11:42:18
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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Would just add the small footnote that default-but-not-contracted sort orders have changed across JVM versions in the past.</div><br id="lineBreakAtBeginningOfSignature"><div dir="ltr">Adam</div><div dir="ltr"><br><blockquote type="cite">在 2024年6月7日，下午8:10，Jeff Allen <ja...@fa...> 写道：<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
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<div class="moz-cite-prefix">This is maybe better as an issue,
although it sounds like one that already defeated us.<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">1. The code by which a call is matched
to a method always looked somewhat heuristic to me. (I believe
this comes from a Greek word meaning "luck".) As I understand it,
it takes the first match, a match ocurring where the arguments say
they can produce the Java type in the signature. The sort order of
overloaded methods is therefore important. I think "What Would
Java Do?" is the aspiration, but I suspect this cannot be achieved
just by sorting. (Have we changed the sort? I didn't think so.)
The best expression of expected behaviour is probably in the tests
`test_joverload.py` and `javatests/Reflection.java`.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">2. There has been some work in the
matching to address variable numbers of arguments, so some code
change, late in 2.7.3 (I think) and in 2.7.4 (currently in beta).
I might have blamed:
<a class="moz-txt-link-freetext" href="https://github.com/jython/jython/commit/dd271a5edaa06925d45ef2d1477e3ec1cf6adfc7">https://github.com/jython/jython/commit/dd271a5edaa06925d45ef2d1477e3ec1cf6adfc7</a>
but I think it is later than you need to explain the change.
However, I think it is a good place to start. These are the source
files right files (probably). Another possible cause is in
"normalisations" that can occur during assignment which I think we
tweaked (to solve another problem, not just for the heck of it).<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">3. You're asking to hook the
`__tojava__` methods, which I don't *think* you can do. It would
be on built-in types too.<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">How is it with 2.7.4b2? I think I
wouldn't delay 2.7.4 for this, but there's always a small hope
your problem has gone away.<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Bets wishes,<br>
</div>
<div class="moz-cite-prefix">Jeff<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">On 06/06/2024 22:38, John Hubbard
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CAO...@ma...">
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<div dir="ltr">
<div dir="ltr">Hello, </div>
<div dir="ltr"><br>
</div>
<div dir="ltr">Has something changed between Jython 2.7.2 and
Jython 2.7.2 with regards to how calls from Jython to an
overloaded Java method are resolved? <br>
<div><br>
</div>
<div><b>Background</b><br>
</div>
<div>I am trying to update our application from Jython 2.7.2
to Jython 2.7.3 and I have run into what I think is a change
in how Jython handles overloaded Java methods. The primary
motivation for the update is proper handling of * imports
under JDK 17 (and JUnit 5); see Jython GitHub issues 105,
304 and maybe 309. </div>
<div><br>
</div>
<div>Our application is primarily Java based but uses Jython
for high level scripts which perform high level sequencing.
One of the most common things those scripts do is construct
'bags of data' which are handled by our AttributeTable class
(full jdoc <a href="https://share.nso.edu/shared/dkist/jhubbard/atst/atst/cs/interfaces/IAttributeTable.html" target="_blank" moz-do-not-send="true">here</a>). That
class is backed by a Map<String, String[]> and stores
heterogenous data via various via getters and setters like:</div>
<blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px">
<div><font face="monospace">insert(String name, String
value)</font></div>
<div><font face="monospace">insert(String name, int value)</font></div>
</blockquote>
<blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px">
<div><font face="monospace">insert(String name, boolean
value)</font></div>
</blockquote>
<blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px">
<div><font face="monospace">...</font></div>
</blockquote>
<blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px">
<div><font face="monospace">String getString(String name)</font></div>
</blockquote>
<blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px">
<div><font face="monospace">int getInt(String name)</font></div>
</blockquote>
<div><br>
</div>
<div>With Jython 2.7.2 I could could write a script like:</div>
<blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px">
<div><font face="monospace">tbl = AttributeTable();</font></div>
<div><font face="monospace">name = 'name'</font></div>
<div><font face="monospace">value = 27</font></div>
<div><font face="monospace">tbl.insert(name, value)</font></div>
</blockquote>
<div>and it would behave as expected. Jython would resolve
the insert call to the Java AttributeTable.insert(String,
int) method, the Java side would then convert the integer 27
into the String "27" and store it in the map for later
use. </div>
<div><br>
</div>
<div><b>Problem</b></div>
<div>With Jython 2.7.3 I think that the truthiness of the
value is being evaluated and AttributeTable.insert(String,
boolean) is what is getting triggered. For example the
following code:</div>
</div>
<blockquote style="margin:0 0 0 40px;border:none;padding:0px">
<div>
<div>
<div><font face="monospace">def savePropertyValue(appName,
propertyName, propertyValue):</font></div>
</div>
</div>
<div>
<div>
<div><font face="monospace"> print('savePropertyValue(' +
str(appName) + ', ' + str(propertyName)</font></div>
</div>
</div>
<div>
<div>
<div><font face="monospace"> + ', ' +
str(propertyValue) + ')')</font></div>
</div>
</div>
<div>
<div>
<div><font face="monospace"> at = AttributeTable()</font></div>
</div>
</div>
<div>
<div>
<div><font face="monospace"> at.insert(propertyName,
propertyValue)</font></div>
</div>
</div>
<div>
<div>
<div><font face="monospace"> at.show('savePropertyValue()
AttributeTable ')</font></div>
</div>
</div>
</blockquote>
<div dir="ltr">
<div>produces </div>
</div>
<blockquote style="margin:0 0 0 40px;border:none;padding:0px">
<div dir="ltr">
<div><font face="monospace">savePropertyValue(atst.ics.visp,
atst.ics.visp.slitStepSz, 0.05)<br>
savePropertyValue() AttributeTable
atst.ics.visp.slitStepSz: true</font><br>
</div>
</div>
</blockquote>
<div dir="ltr">
<div><br>
</div>
<div>So the value 0.05 was passed into the jython
savePropertyValue function but what ended up being inserted
into the Java AttributeTable object was the boolean true. </div>
<div><br>
</div>
<div><b>Questions</b></div>
<div>
<ol>
<li>What is the expected behavior when interacting with
overloaded Java objects? Were we just lucky before and
this was never expected to work?</li>
<li>Is anyone aware of changes on the Java side that may
have triggered this? I'd like some background on what
might have caused this so I can investigate what might
be improved to fix this.</li>
<li>Is it possible to inject custom PyObject --> Java
Object coercion routines? The interpreters are setup at
a high level; if I could mask the Java AttributeTable
class with a Python class that better handled overloaded
methods and then somehow coerce/convert it to an Java
AttributeTable before sending it back into Java land I
might be able to work around this.</li>
</ol>
<div>Thanks</div>
</div>
<div><br>
</div>
<div>
<div>
<div dir="ltr" class="gmail_signature">
<div dir="ltr">--
<div>Cheers</div>
<div>-john</div>
</div>
</div>
</div>
</div>
</div>
</div>
<br>
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</blockquote>
<pre class="moz-signature" cols="72">--
Jeff Allen
</pre>
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