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What's in a empty class?
Oct 27, 2015
TheFlyingFiddle
Oct 27, 2015
Adam D. Ruppe
Oct 27, 2015
TheFlyingFiddle
October 27, 2015
Gravatar of TheFlyingFiddlePosted by TheFlyingFiddleReply
TheFlyingFiddle
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With this code:

class A { }
pragma(msg, __traits(classInstanceSize, A));

I get the output 8 (32-bit).
I can account for the first thing a vtable. But that
should only cover 4bytes. What's in the other 4bytes?
October 27, 2015
Gravatar of Adam D. RuppePosted by Adam D. Ruppe
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Adam D. Ruppe
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On Tuesday, 27 October 2015 at 21:23:45 UTC, TheFlyingFiddle wrote:
> I can account for the first thing a vtable. But that
> should only cover 4bytes. What's in the other 4bytes?

The monitor used for `synchronized`.

(yes, this is something a lot of people want to remove as it is rarely all that useful yet you pay the price in all D class objects)
October 27, 2015
Gravatar of TheFlyingFiddlePosted by TheFlyingFiddle
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TheFlyingFiddle
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On Tuesday, 27 October 2015 at 21:28:31 UTC, Adam D. Ruppe wrote:
> On Tuesday, 27 October 2015 at 21:23:45 UTC, TheFlyingFiddle wrote:
>> I can account for the first thing a vtable. But that
>> should only cover 4bytes. What's in the other 4bytes?
>
> The monitor used for `synchronized`.
>
> (yes, this is something a lot of people want to remove as it is rarely all that useful yet you pay the price in all D class objects)

I see Thanks.