On Fri, 01 Aug 2014 01:07:55 -0400, Jonathan M Davis <[email protected]>
wrote:
On Thursday, 31 July 2014 at 20:49:18 UTC, Timon Gehr wrote:
On 07/31/2014 09:37 PM, Jonathan M Davis wrote:
disable contracts, turn assert(0) into a halt
instruction, and disable bounds checking in @system and @trusted code.
So, if you want to keep the assertions and contracts and whatnot in,
Unfortunately, if used pervasively, assertions and contracts and
whatnot may actually hog the speed of a program in a way that breaks
the deal.
Disabling assertions (and whatnot), assuming assertions to be true (and
disabling whatnot) and leaving all assertions and whatnot in are
different trade-offs, of which assuming all assertions to be true is
the most dangerous one. Why hide this behaviour in '-release'?
I'm afraid that I don't see the problem. If you want assertions left in
in your release/production builds, then don't use -release. If you want
them removed, then use -release. Are you objecting to the fact that the
compiler can do further optimizations based on the fact that the
assertions are presumed to be true if they're removed? I really don't
see any problem with that. You're screwed regardless if the assertions
would have failed. By their very nature, if an assertion would have
failed, your program is an invalid state, so if you don't want to risk
having code run that would have failed an assertion, then just don't
compile with -release. And if you are willing to assume that the
assertions won't fail and have them disabled in your release build, then
you might as well gain any extra optimizations that can be made from
assuming that the assertion is true. You're already making that
assumption anyway and potentially letting your program enter an invalid
state.
This is not tenable. I realized when developing a library with classes,
that not doing -release, means every virtual call is preceded and followed
by a call to assert(obj), which calls Object.invariant -- a virtual call.
Even if you don't define any invariant, it's still called (maybe final
classes are better, but I'm not sure).
The cost for this is tremendous. You may as well not use classes.
-Steve
