Article: Why Const Sucks

[Jonathan M Davis]

On Tuesday, March 06, 2018 10:47:36 H. S. Teoh via Digitalmars-d-announce 
wrote:
> On Tue, Mar 06, 2018 at 01:31:39PM -0500, Steven Schveighoffer via 
Digitalmars-d-announce wrote:
> > On 3/6/18 10:39 AM, Jonathan M Davis wrote:
> > > Yeah. If you're dealing with generic code rather than a specific
> > > range type that you know is implicitly saved when copied, you have
> > > to use save so often that it's painful, and almost no one does it.
> > > e.g.
> > >
> > > equal(lhs.save, rhs.save)
> > >
> > > or
> > >
> > > immutable result = range.save.startsWith(needle.save);
> >
> > Yep. The most frustrating thing about .save to me is that .save is
> > nearly always implemented as:
> >
> > auto save() { return this; }
> >
> > This just screams "I really meant just copying".
>
> Yeah, and also:
>
>   auto save() {
>       auto copy = this;
>       copy.blah = blah.dup;
>       return this;
>   }
>
> Which just screams "I'm really just a postblit in disguise".

That's exactly what it is. It's a postblit constructor that you have to call
manually and which works for classes and dynamic arrays in addition to
structs.

- Jonathan M Davis