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Subject: Re: [std-proposals] Make 'this' a reference
From: Gašper Ažman (gasper.azman_at_[hidden])
Date: 2020-03-05 03:53:16


You can have the behaviour when deducing this (p0847) lands.

On Thu, Mar 5, 2020 at 9:28 AM Andrey Semashev via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> On 2020-03-05 11:59, Jake Arkinstall via Std-Proposals wrote:
> > I'd choose a different new keyword rather than add a new rule on 'this'
> > which is bound to have some confusing edge cases (especially when
> > passing this to template functions - does it resolve as a pointer? A
> > reference? A special object that tries to behave as both?).
> >
> > I'd personally go with self *≡* *this, such that self.member =
> this->member.
>
> The problem is that `self` is already used in code base. Ironically,
> often to emulate `this` (e.g. in a proxy class that refers to the real
> object with a `self` data member).
>
> > On Thu, 5 Mar 2020, 08:50 Marian Darius via Std-Proposals,
> > <std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]>>
>
> > wrote:
> >
> > It feels weird that inside a class the keyword 'this' is a pointer
> > to the current object, when it has reference semantics:
> > - it is not re-assignable
> > - it is not null (as not null as a reference can be)
> >
> > It seems a natural fit for 'this' to be a reference, making the
> > meaning of '&&', 'const&&' and 'const&' qualified methods
> > a little more intuitive (that becomes the type of 'this' in that
> > method).
> >
> > The biggest problem with changing 'this' to a reference is
> > backwards-compatibility. But we already have a feature in
> > this language that we can look at to solve this issue: function
> > references convert to function pointers back-and-forth implicitly.
> > Here is a simple example: https://compiler-explorer.com/z/EdVLD4
> >
> > So we could make 'this' a similar style of reference that implicitly
> > converts to a pointer when needed (for example, when using '->'
> > operator or passing to a function taking a pointer).
> >
> > Disclaimer: I am not an expert, and this is not a well thought-out
> > proposal. I just want some feedback on the idea and on whether I
> > should maybe write a formal proposal for it.
> >
> > Is this something that interests people? It feels like it might make
> > the language easier to use and understand, especially to beginners.
> >
> > Was this proposed before? If so, what happened to that proposal?
> > Is there something hopelessly broken that I didn't think of that can
> > make this unfeasible?
> >
> > Darius
> > --
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> Std-Proposals_at_[hidden]>
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> >
> >
>
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