On Wednesday, 10 June 2015 at 16:03:17 UTC, Andrei Alexandrescu
wrote:
On 6/10/15 8:41 AM, Brian Rogoff wrote:
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.
I agree. I'm one of those folks who think circular dependencies
are fine, thank you very much, and the few cases in which it
causes problems should be flagged and diagnosed in a principled
way.
Everybody also likes:
* recursion and mutual recursion of any depth (there's a lot
more of it going in the usual programs than one might think)
* recursive and mutually recursive types
* declaring top level names in any order and they just "work"
But all of a sudden, people get sugar in their gasoline and
sand in their gears when they hear of the same thing applied to
modules. I suspect it's because some legacy languages didn't
quite do a stellar job at it. Figuring that stuff out and
pointing out problems is exactly the kind of thing computers
are good at and humans, not so good.
Andrei
Cyclic imports create problems that do not exists with forward
declaration. This is surprisingly hard to get a well defined
behavior for compile time feature. I would argue to make them
illegal, but that is still a good idea to avoid them when
possible.
