Isn't "transitive" the wrong word?

[Steven Schveighoffer]

"Janice Caron" wrote
> On 04/04/2008, Manfred Nowak wrote:
>> Janice Caron wrote:
>>
>>  > So the relation is
>>  [...]
>>
>>  y is reachable from x (through a series of pointers for example)
>>
>>
>>  Reachable is transitive:
>>
>>   if z is reachable from y
>>  and y is reachable from x
>>
>>  then
>>
>>     z is reachable from x
>>
>>
>>  In D the transitivity of reachability carries over to const:
>>
>>   if x is const
>>  and z is reachable from x
>>
>>  then
>>
>>     z is const
>
> My apologies for being thick, but I still don't get it. What /exactly/
> is the binary relation R, such that:
>
> (1) (a R b) and (b R c) implies (a R c), is true in D
> (2) (a R b) and (b R c) implies (a R c), is false in C++
>
> I still can't figure that out. Am I just missing something obvious?
>
> And even assuming there is such an R, wouldn't it make more sense to
> say "R is transitive", rather than "const is transtive"?
>
> Help me - I'm confused.

If c contains b, and b contains a, then the R becomes "is made const by"  So 
you have:

if(a is made const by b) and (b is made const by c) then (a is made const by 
c)

True in D, false in C++.

-Steve