On 28 Sep 2011, at 04:42, Ben Robinson wrote:
On Tue, Sep 27, 2011 at 11:09 AM, Dave Abrahams <dave@boostpro.com> wrote:
on Tue Sep 27 2011, Gennadiy Rozental <rogeeff-AT-gmail.com> wrote:
Dave Abrahams <dave <at> boostpro.com> writes:
Now if you can come up with another approach to test these expectations I'd be happy to listen.
We already have an approach; it requires integration with the test system. Yes, it's imperfect, but it does do the kind of testing needed to see that MyComponent<int> is prohibited.
Can you elaborate on this in greater detail? Currently, if I want to prove
a static assertion fails, my admittedly cumbersome technique is to uncomment the test for that condition, compile to produce the error, then re-comment out the test. This becomes very tedious for large numbers of regression tests.
Because we have quite a lot of these kinds of tests, we have added to our private tester code the following: If you use wrap code in: #ifdef DM_FAILING_CODE_UNIQUEID (where you can change UNIQUEID to different values) #endif (which we find by grepping. The ifndef is to make it more likely we'll notice a mis-spelling of the macro) Then the tester does: 'compiling file.cc should pass, compiling with each of the DM_FAILING_CODE_UNIQUEIDs turned on should fail. This makes it possible to write tests like: #include <utility> int main(void) { std::pair<int, int> p; std::pair<void*, void*> q; #ifdef DM_FAILING_CODE_ASSIGN p = q; #endif #ifdef DM_FAILING_CODE_EQUALS p == q; #endif } I don't know if such a thing would be interesting to boost. It would seem much simpler, while still allowing one to write compact compile-time tests, rather than needing many, many files. The only problem we have had is that it is easy to miss a mis-spelt DM_FAILING_CODE, so we are thinking about changing to #ifndef instead, to make them more likely to be caught :) Chris
Thank you,
Ben Robinson, Ph.D.
--
Dave Abrahams BoostPro Computing http://www.boostpro.com
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