[Issue 6857] Precondition contract checks should be statically bound.

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=6857


Stewart Gordon <smjg at iname.com> changed:

           What    |Removed                     |Added
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                 CC|                            |smjg at iname.com


--- Comment #20 from Stewart Gordon <smjg at iname.com> 2012-05-03 16:45:21 PDT ---
(In reply to comment #5)
> This is incorrect.  It must satisfy the precondition for A or any 
> class derived from A.

The in contract is part of the API of class A.  If you call a method of A with
arguments that don't satisfy this contract, you are not conforming to the API.

(In reply to comment #10)
> It isn't a bug, it is the way it is supposed to work.  Nor am I 
> ignoring it - I'm trying to explain it.

You're explaining the design you're copying.  That's quite different from
explaining why you've chosen to copy this particular design to the letter.

(In reply to comment #19)
> (In reply to comment #16)
>> This is the issue.  WHY are they done based on the virtual type?  
>> Checking the contracts based on static typing would detect logical 
>> errors in the calling code.  Doing it based on the virtual type 
>> ignores latent bugs in specific instances where they are harmless.  
>> I can't understand why that's a good idea.
> 
> The whole idea of polymorphism is to base things on the virtual 
> type.

What are "things"?

If you mean the effect of a call, then yes.  This we seem to be all agreed on.

If you mean whether a given call is legal, then you could by the same argument
insist that called method names must be resolved in the context of the virtual
type.

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