DIP 1009--Improve Contract Usability--Preliminary Review Round 1

[H. S. Teoh via Digitalmars-d]

On Thu, Jun 22, 2017 at 06:17:54AM +0000, MysticZach via Digitalmars-d wrote:
> On Wednesday, 21 June 2017 at 19:34:53 UTC, H. S. Teoh wrote:
> > This is a sticky point about D's current DbC implementation that
> > myself and several others feel is a design flaw. In particular, that
> > in-contracts are executed as part of the *callee*, when the intent
> > of DbC is really that it is the obligation of the *caller* to
> > fulfill its stipulations, and therefore the contract verification
> > should happen at *caller* site rather than at the beginning of the
> > callee.
> > 
> > This particular implementation detail causes problems with
> > binary-only libraries: most library vendors would prefer to ship the
> > library compiled with -release rather than not, but in -release, the
> > asserts in any in-contracts would be elided, making them essentially
> > non-existent by the user uses the library.  So you either have to
> > dispense with DbC altogether, or be forced to ship two versions of
> > your library, one with contracts compiled in and one without, in
> > order for your users to benefit from DbC *and* not have to suffer
> > performance penalties in their own release builds.
[...]
> But on the other side, binary-only libraries published in release mode
> are actually rare in D, right?

Rare or not, if we want D to grow, we cannot ignore proprietary usage,
which would most likely involve binary-only libraries.  Precluding this
(or at the very least discouraging it) just because of a design flaw in
D's implementation of DbC would be a grave strategic error on our part.


T

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