Difference between revisions of "Talk:Objectless Calls"
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     end
 
     end
 
</e>
 
</e>
 +
 +
----
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--[[User:Peter gummer|Peter gummer]] 04:42, 15 March 2008 (PDT) The redefinition of <e>is_valid_value</e> is strengthening the precondition. This is contrary to Design by Contract. I think you have a valid point, Paul, but you need to come up with a decent example!

Revision as of 02:42, 15 March 2008

Why couldn't the client needing to validate parameters inherit{NONE} from A_VALIDATOR instead of creating an instance?

Also your validation feature doesn't have a postcondition so it's really an incomplete contract. If your validation feature is supposed to ensure something, it needs to state that, otherwise you're just saying, in order to create this object it needs to satisfy this routine which can be overidden and since there's no postcondition, it could be overridden to mean anything including nothing and that's a bug.

Non-polymorphic inheritance shouldn't have a performance hit unless it's not being optimized, by definition they're monomorphic calls so they can be static and inlined.


--Clemahieu 14:43, 14 March 2008 (PDT) 

class A_CLIENT
inherit{NONE}
A_VALIDATOR
feature
process (a_value: ?VALUE)
    local
        l_a: A
    do
        if is_valid_value (a_value) then
            create l_a.make (a_value)
            ...
        end
    end

--Peter gummer 04:42, 15 March 2008 (PDT) The redefinition of is_valid_value is strengthening the precondition. This is contrary to Design by Contract. I think you have a valid point, Paul, but you need to come up with a decent example!

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