Private visible?

Lucas Goss lgoss007 at gmail.com
Thu Jul 13 13:58:45 PDT 2006


Walter Bright wrote:
> 
> The original reason why private members would be visible but not 
> accessible has been forgotten. However, there were some significant 
> issues brought up with making them invisible:
> 
> 1) function overloading - if various overloads of a function have 
> different protections, different functions will be selected even though 
> the same arguments are presented. This can be surprising when code is 
> moved around. If they are visible, you'll get an error message instead 
> of silently varying behavior.
> 
> 2) function overloading - one could lose the ability to 'poison' an 
> operation on certain argument types, because instead the private 
> function will not be seen and another selected.
> 
> 3) function overriding - if a private function in a derived class 
> overrides a public one in a base class, this overriding will not happen 
> if the private function is invisible. Not only does this break 
> encapsulation, it prevents the design pattern of being able to 'poison' 
> certain operations on a class.

Interesting. But if I use a third party library:

import lib.thirdparty;
...
commonFuncName() // error (declared in my module and in thirdparty)

I would be dumbfounded. Especially when I look at there documentation 
and there is no "commonFuncName".

I had some more thoughts... but I lost them in the midst of other 
responsibilities. I'll see if I can remember.

Lucas



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