Incidentally...
On 28. 3. 2016, at 18:10, OC <[email protected]> wrote:
> completely absurd and very anti-object-oriented) “Cannot cast object”
> exception.
... this reminded me of a problem I so far haven't been able to find a proper
solution for: how the heck do you proxy in Groovy?
In ObjC, I can write
===
@interface AnyClassOfMine:Beanlike
@property NSString *name;
@end
@implementation AnyClassOfMine @end
@interface DumbProxy:Beanlike
@property id server;
@end
@implementation DumbProxy
-forwardingTargetForSelector:(SEL)sel { return self.server; }
@end
id objects=@[[AnyClassOfMine new:@"name":@"Direct"],[DumbProxy
new:@"server":[AnyClassOfMine new:@"name":@"Proxied"]]];
for (AnyClassOfMine *o in objects) NSLog(@"got %@",o.name);
===
and it works precisely as assumed, writing out
===
2016-03-29 17:57:37.501 a.out[5387:707] got Direct
2016-03-29 17:57:37.503 a.out[5387:707] got Proxied
===
(Note if interested: the Beanlike superclass is irrelevant, it just simulates
the new Foo(bar:bax) functionality of Groovy, which ObjC does not have, by
implementing the new:(property-name):(value) method.)
Groovy -- unlike pure Java -- is smart enough to allow me to _implement_ such a
proxy, but for sweet world, I cannot find a way to _use_ it?
===
class AnyClassOfMine {
def name
}
class DumbProxy {
def server
def propertyMissing(String name) {
server."$name"
}
}
def objects=[new AnyClassOfMine(name:"Direct"),new DumbProxy(server:new
AnyClassOfMine(name:"Proxied"))]
for (AnyClassOfMine o in objects) println "got $o.name"
===
Alas, instead of working as expected, this fails with the aforementioned
nonsensical exception:
===
got Direct
Caught: org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot
cast object 'DumbProxy@73f43791' with class 'DumbProxy' to class
'AnyClassOfMine'
...
===
How do you write and use a proxy in Groovy, so that it works properly?
(Note: “for (o in objects) ...” would work is this case, but would bring other
problems, e.g., if there was a method “foo(AnyClassOfMine obj)“ called as “for
(o in objects) foo(o)”, it would cause “No signature of method is applicable
for argument types: (DumbProxy)”.)
Thanks a lot,
OC
