Copy a struct and its context

[Yuxuan Shui via Digitalmars-d-learn]

On Tuesday, 13 September 2016 at 01:32:19 UTC, Steven 
Schveighoffer wrote:
> On 9/12/16 4:11 PM, Ali Çehreli wrote:
>> On 09/10/2016 10:44 PM, Yuxuan Shui wrote:
>>> I recently noticed nested struct capture its context by 
>>> reference
>>> (which, BTW, is not mentioned at all here:
>>> https://dlang.org/spec/struct.html#nested).
>
> " It has access to the context of its enclosing scope (via an 
> added hidden field)."
>
> It needs to be a reference. Otherwise, you store the entire 
> stack frame in the struct? That wouldn't be a "field". It also 
> has write access to the context:

Why not just capture the variables that are actually been 
referenced? Also being a field doesn't put limits on the size of 
the "field".

I like how C++ lambda lets you choose what variables to capture, 
and how are they captured. I'm little disappointed that D doesn't 
let me do the same.