Groovy映射作为JRuby中的接口方法

Posted 2021-02-26

Groovy has the as keyword which enables the implementation of a Java interface by using the as keyword, its quite easy to mimic this in JRuby.

module InvokableHash
   def as(java_ifc)
     # Each method will create a key in the hash which points to a block
     # which is called 
     java_ifc.impl {|name, *args| self[name].call(*args)}
   end
end
 
class Hash
   include InvokableHash
end
 
impl = {
 :i => 10,
 :hasNext => proc { impl[:i] > 0 },
 :next => proc { impl[:i] -= 1 }
}
 
iter = impl.as java.util.Iterator
while (iter.hasNext)
   puts iter.next
end