Re: [boost] [type traits] add a set of templates to propagate constetc from one type to another?

Subject: Re: [boost] [type traits] add a set of templates to propagate constetc from one type to another?
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2010-03-03 13:39:09

Jeffrey Hellrung wrote:
> Stewart, Robert wrote:
>
> > However, if From already is const, copying "const" from To
> > to From won't make From any more const, so "copy" does
> > capture the augmentation idea pretty well.
>
> I'm tending to interpret "copy" as overwrite or replace whatever cv
> qualifiers are on To with whatever is on From, rather than "augment".
> This might be a stretch, but that seems consistent with the
> use of the word copy elsewhere, e.g., std::copy.

std::copy doesn't necessarily affect existing elements.  The use of "copy" is a bit varied.

> > "Propagate" is probably not a good choice because it
> > doesn't quite imply the addition to existing state you mean,
> > at least to me.
>
> A common meaning of "propagate" is "to pass along to
> offspring", which seems appropriate enough here.

But the offspring doesn't have anything not provided by its progenitors.  Thus, it isn't augmentation but creation.

> I'll point out that the original poster also chose the word
> "propagate" independently of myself.

I understand, but just as you are concerned about "copy," I'm reporting that "propagate" doesn't help me.

> > Furthermore, "propagate" is frequently misspelled as "propogate."
>
> I understand your concern here., but I consider this a minor
> issue at best.

I just wanted to note that folks are likely to make many more mistakes with "propagate" than "copy" that compilers will happily report, but developers will curse.

> > "Augment" seems a bit stilted, but it does capture the idea
> > well.  "Add" actually captures the idea pretty well, but we
> > can't use that.
>
> Both fail to convey the directionality and "from-to" or "source-dest"
> nature of the operator.

That applies to "copy" and "propagate" just as easily.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer, Core Software      using std::disclaimer;
Susquehanna International Group, LLP  http://www.sig.com

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