What is going on here?

Steven Schveighoffer via Digitalmars-d digitalmars-d at puremagic.com
Wed Mar 4 09:19:31 PST 2015

On 3/4/15 11:32 AM, "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm at gmx.net>" 
> On Wednesday, 4 March 2015 at 15:43:15 UTC, 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);
> The spec says [1], that the first write to a field in a class's
> constructor is a construction, not an assignment. I assume this applies
> to structs as well. If so, this implies that the compiler already knows
> at each point which fields are already constructed. Why doesn't it
> automatically insert appropriate destructor calls then?
> [1] http://dlang.org/class.html#field-init

That is talking about initializing immutable fields. The dtor is not 
called when the exception is thrown, but this doesn't seem to be in the 
spec (I don't remember where I read it, but I'm sure it's an intentional 
decision). D provides a mechanism to destroy partially constructed 
objects, use scope(failure).


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