Re: [boost] [Phoenix-3] Is Actor assignable?

Subject: Re: [boost] [Phoenix-3] Is Actor assignable?
From: Thomas Heller (thom.heller_at_[hidden])
Date: 2011-01-22 09:13:23

Joel de Guzman wrote:

> On 1/22/2011 9:02 PM, Joel de Guzman wrote:
>> On 1/22/2011 8:17 PM, Thomas Heller wrote:
>>> Joel de Guzman wrote:
>>>
>>>> On 1/21/2011 8:39 PM, Michel MORIN wrote:
>>>>> I have another question about Phoenix 3.
>>>>> Is the copy assignment of Actors no-op, or does it really copy the
>>>>> contents?
>>>>>
>>>>> Actor a;
>>>>> Actor b = ...;
>>>>> a = b; // no-op?
>>>>
>>>> It should copy the contents. Thomas?
>>>
>>> Not really. It needs to create the assign actor (that means the
>>> expression template representing the assignment operation.
>>> It is neither a no-op nor is the assignment "executed". Remember the
>>> stuff about phoenix being lazy ;)?
>>
>> No! That's not the case here. There *is* still the immediate assignment
>> operator being called when two actors are of the same type (e.g.
>> when lhs and rhs are phoenix values). In these cases, a *is*
>> assigned to *b*. Thus, for values, the contents are copied.
>> Ditto for copy construction of course.
> 
> Oops, I meant b is assigned to a of course :-P

Seems like i don't stand a chance. I was trying to find a use case where you 
might want the lazy version of the assignment ... couldn't find one.
Added the operator=(actor const&) to phoenix 3.

Thanks for the hint.

Regards,

Thomas