What is going on here?

[Steven Schveighoffer via Digitalmars-d]

On 3/4/15 2:31 PM, Shachar Shemesh wrote:
> On 04/03/15 17:43, Steven Schveighoffer wrote:
>> On 3/4/15 8:43 AM, Shachar Shemesh wrote:
>>
>>> I'd expect A's destructor to run, which does not seem to be the case.
>>
>>
>> I believe destructors are not run when you throw inside a constructor.
>> So plan to deallocate if the ctor throws:
>>
>> a = A(var + 1);
>> scope(failure) destroy(a);
>>
>> -Steve
>
> That's pretty horrible. So now I need to keep track of the
> implementation of my members to figure out whether it is okay to skip
> the destructor or not.

Why does it matter? If the member is constructed, insert a 
scope(failure) destroy, otherwise don't. Or don't throw in the ctor and 
mark it nothrow, then you don't have to worry about it at all.

> All of this from a language that claims to support RAII, which was
> invented precisely so the programmer does not have to keep track of
> those things.

It would be nice if there is a way. D, unlike C++, does not separate 
construction of members from the code. This means the situation is not 
as easy to solve.

But an interesting question -- when constructing a struct or class, 
isn't every member initialized with it's init value anyway? Why would 
calling dtor on that be bad?

-Steve