[General] Encapsulation in LK

[Daniel Ingalls]

hi, it does not look like LK provides any language extension to help
with encapusulation, so all the properties of LK "classes" are public,
isn't it?

Hi Haowei -

Yes.  I have been pushing to augment our current "extends" construct  
with a message category name, so that the browser can give a bit more  
help in the case of major classes.  I believe this would be the place  
to add a public/private distinction as well.

It's true that without a type system it is harder to guarantee proper  
behavior, but in my view 90% of the value is in highlighting the  
public protocol so the system is more understandable, and authors are  
motivated to make it so.

The fact is that with our cool method-wrapping metasystem (that we use  
for profiling of various sorts) it would be easy (truly only a couple  
of lines of code!) to implement a test mode in which the system ran  
with dynamic checks for violation of private access.  This is not a  
guarantee of conformance, but  it would catch violations in any code  
that actually ran.  I think we'd be very happy with the result.

Thanks for your interest

	- Dan