I read Eric Lippert's article on default property semantics in VBScript: http://blogs.msdn.com/b/ericlippert/archive/2005/08/30/458051.aspx
It says:
The rule for implementers of IDispatch::Invoke is if all of the following are true:
- the caller invokes a property
- the caller passes an argument list
- the property does not actually take an argument list
- that property returns an object
- that object has a default property
- that default property takes an argument list
then invoke the default property with the argument list. Strange but true.
This seems on its face to be an odd rule, but it's invaluable when you're working with collections. Or at least, it would be, but I can't seem to get it to work.
class Test1
public property get foo
set foo = new Test2
end property
end class
class Test2
public default property get bar (arg)
Response.Write arg
end property
end class
dim t: set t = new Test1
Response.Write TypeName(t.foo) ' => "Test2"
t.foo.bar("Hello, World!") ' => "Hello, World!"
t.foo("Hello, World!") => "Microsoft VBScript runtime error '800a01c2' / Wrong number of arguments or invalid property assignment: 'foo'"
The caller invokes the foo
property and passes an argument list. The foo
property does not actually take an argument list. The foo
property returns an object of type Test2
. Test2
has a default property, bar
. That default property takes an argument list.
Is this a bug, or am I misunderstanding either the default property semantics or my code?
Well golly. I would have expected that to work. It's probably a bug in the implementation of VBScript property getters, which would make it my fault. Sorry about that.
Since the last person to touch that code was me in 1998, I wouldn't expect a fix to be forthcoming any time soon.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With