Hello Camel Developers what about this:
public class LoadBalanceDefinition<Type extends ProcessorDefinition<Type>>
extends ProcessorDefinition<Type> {
...
public LoadBalanceDefinition<Type> roundRobin() {
...
@SuppressWarnings("unchecked")
public Type to(String uri) {
return (Type) this;
}
...
}
Thus you preserve the type safety and you example works.
Regards,
Mitko
From:
Claus Ibsen <claus.ib...@gmail.com>
To:
dev <dev@camel.apache.org>
Date:
17.02.2011 09:49
Subject:
[DISCUSS] - Java DSL caveat with the Content Based Router
Hi
DSL in plain Java is somewhat limited how far you can go with Java and
Generics.
A common issue over the times has been the Content Based Router where
users would use other "complex patterns" inside the when/otherwise
blocks.
By complex patterns I mean patterns which have additional DSL for
configuration. Or for example multicast or load balancer which re-uses
the commons DSL's, but under the given mode (eg multicast or load
balancing).
To indicate when the pattern "ends" you would have to use .end() and
the DSL would return back the scope to the previous pattern. But
that's not possible, as the Java Generics Type System sucks for doing
DSLs.
I have been experimenting to see if there was a way to tell in the
end, which "scope" to return back to. So in the Content Based Router
example, you could indicate: Choice, eg
.end(ChoiceDefinition.class)
But that doesn't work.
So the best solution I have found is as follows:
from("direct:start")
.choice()
.when(body().contains("Camel"))
// we need to use endChoice to tell Java
DSL to return scope back to the choice DSL
.loadBalance().roundRobin().to("mock:foo").to("mock:bar").endChoice()
.otherwise()
.to("mock:result");
If you don't have .endChoice() then the code above will not compile.
By introducing a method named: endChoice, we can force the Java DSL to
return back to the CBR scope.
Since this problem mostly manifests itself with the Content Based
Router, then I think this is the best we can do as far.
However do you think endChoice is a good name? It may indicate it ends
the entire CBR block?
We could also name it
- asChoice
- endAsChoice
- endAndBackToChoice
- backToChoice
- scopeAsChoice
Any good name?
--
Claus Ibsen
-----------------
FuseSource
Email: cib...@fusesource.com
Web: http://fusesource.com
Twitter: davsclaus
Blog: http://davsclaus.blogspot.com/
Author of Camel in Action: http://www.manning.com/ibsen/
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