On Wednesday, 10 June 2015 at 06:55:43 UTC, Walter Bright wrote:
On 6/9/2015 10:39 PM, deadalnix wrote:
The actual code is far more complex than the presented sample
:)
That what I'm trying to do in general, but here I'm faced with
cases that are
very hard to untangle.
The 'tangle' of cyclical import graphs, as you so appropriately
put, is not only hard on the compiler, it makes it much harder
for human readers to make sense of code. Even reading your
little code snippet hurts my brain.
Go, in one of their better decisions, decided "Thou Shalt Not
Have Import Cycles". This forces users to untangle their code,
and I believe that is A Good Thing.
I'd like to do that for D, but of course it is far too late for
that.
Ada (83 and 95) were also rigid about not allowing any kind of
import cycles. At some point, probably after Ada 95 when OO was
added, it was decided after much experience that there were some
cases where it was better to allow it. If you're interested, in
the Ada world this issue was dubbed "the with-ing problem" and a
quick Google search gives
http://www.ada95.ch/doc/within/FAQ.html#what
http://www.adaic.org/resources/add_content/standards/05rat/html/Rat-4-2.html
also in the world of Haskell, this thread
https://mail.haskell.org/pipermail/haskell-cafe/2004-September/006885.html
and I'm sure in many other places too.
I agree with you, Walter, that mutual recursion amongst imports
is usually bad, but I think you inadvertently made the right
decision by allowing it in D, and that the bug should be fixed.
If people overuse it to write messy code then the community
should tell them to write that code better.
