The problem here is that you're not giving the Clojure type inferencing
enough info to work with and it's using reflection to find the correct
method. When it finds multiple potential matching methods by arity, it
calls an arbitrary one (not my favorite behavior). So, not a feature and
maybe a bug (or maybe just "undefined behavior", depending how you think
about it).
The start of the problem is that br is not automatically given a type -
it's just treated as an Object. So the method getBaseNullSupplier is
invoked reflectively and the return type of that is just defaulted to
Object, which means it will reflectively find multiple matches for method_
and may call any of them.
The simplest fix is to tag your br var with it's type:
(def ^SupplierRouter br (new SupplierRouter))
Then the inferencer can figure out the rest of it automatically.
Alternately, you could tag just the first call with br:
(println (. br method_ (. ^SupplierRouter br getBaseNullSupplier)))
And that should be enough as well. If this was in a function, I would tag
the incoming parameter instead.
On Sunday, November 6, 2016 at 10:02:42 AM UTC-6, Alexey Stepanov wrote:
>
> Hello!
>
> I experimented with overload resolution. And faced with a strange
> behavior.
>
> https://gist.github.com/alejes/355881c1711224d5a773fbf0275b4898
>
> The Clojure code calls a method from the Java. But at different runs I get
> the result call different methods (4 and 6).
> It is a simplified version of the example which I encountered. In the
> original version it periodically called method #0. However, in the
> simplified example I is not noticed call #0 method.
>
> It is a bug or feature? Can someone explain why is this happening?
>
> Thanks.
>
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