Re: [boost] [variant2] Need rationale for never-empty guarantee

Subject: Re: [boost] [variant2] Need rationale for never-empty guarantee
From: Robert Ramey (ramey_at_[hidden])
Date: 2019-03-01 18:17:16

On 3/1/19 10:05 AM, Steven Watanabe via Boost wrote:
> AMDG
> 
> On 3/1/19 9:50 AM, Robert Ramey via Boost wrote:
>>
>> C++ starts from the idea that every instance should be mutable and hence
>> gives you an assignment operator by default.  The design discussions
>> around variant (expected, outcome, ...) presume that this operation must
>> be implemented.  I question this.  Not only for variant, but for many
>> other C++ data types.
>>
> 
> If you want a variant without assignment, it's
> called const variant<>

LOL - of course you're right. But I was wondering if this would inhibit 
the inclusion of all of the now unnecessary overhead - double buffering 
etc - even it isn't actually used.  Then there's a question about the 
move operator.   In my usage, that seems like a legitimate usage - but 
const would inhibit. Offhand I don't know what this means for swap. So I 
still have questions.

Robert Ramey

> 
> In Christ,
> Steven Watanabe
> 
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