Another idiom I wish were gone from phobos/druntime

[via Digitalmars-d]

On Thursday, 5 February 2015 at 07:28:36 UTC, Paulo Pinto wrote:
> I miss the point about in.
>
> DbC as presentend by Eiffel and adopted in .NET, Ada among 
> others, the complete contract is on the  callee.
>
> It doesn't make sense otherwise.

Conceptually the precondition is a specification that the caller 
has to guarantee, and the postcondition is a specification that 
the callee guarantees. The enforcement of the contract 
specification should be done by the build system which is 
"neutral".

I.e. the contractors who wrote the code for the callers and 
callees may try to subvert the contract, but the build system 
should ideally prevent this. This is of course messed up in D, 
since you don't have a separate specification independent of the 
implementation, but you could still verify the D code against a 
specification to prevent contractors from subverting contracts.

The thought of having the signature/specification before the 
implementation was a good one, but readability suffers from 
having all the braces. So the D syntax is not as usable as it 
should be.

I think D should do this in the body like other languages:

func(){
    @require(...);
    @ensure(…);
    ... function body ...
}

or

func(){
    @pre(...);
    @post(…);
    ... function body ...
}

or

func(){
    pre_assert(...);
    post_assert(…);
    ... function body ...
}