On 5/30/18 11:50 AM, Stefan wrote:
On Wednesday, 30 May 2018 at 13:26:53 UTC, Steven Schveighoffer wrote:
On 5/30/18 8:09 AM, DigitalDesigns wrote:
... it's really really hard to make it check real dependencies.
For serious dependency checking, you could try
https://github.com/funkwerk/depend.
It's used in quite large commercial projects.
OK, so a couple things:
1. The cycle checking has to be really really fast, and run in a small
amount of memory. It runs on startup of EVERY D program. I would LOVE to
get rid of this problem, but unless we either invent our own
object/linker system, or create some tools to work on the linked binary,
we have to do this.
2. The cycle algorithm is fast and works correctly, given the
dependencies that the compiler has provided. It's really not the cycle
algorithm that is the problem, but the determination of dependencies. In
other words, the problem is the compiler not tracing all the actual
dependencies and outlining that in some structure to be parsed later
during program startup.
As you increase the number of dependency points, and therefore the graph
size, the cycle algorithm has to take longer to figure out if there are
any cycles. So even if we can fix the problem outlined here, the cost
may not make it worth the effort!
There are some ideas Martin and I have fleshed out a bit, which would
help reduced the cyclic dependencies, but so far, nobody has had the
time and/or skills to implement. For instance:
https://issues.dlang.org/show_bug.cgi?id=16265
https://github.com/dlang/druntime/pull/1602#issuecomment-231527759
-Steve
