Re: [boost] [boost::endian] Summary of discussion #1

Subject: Re: [boost] [boost::endian] Summary of discussion #1
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2010-06-02 15:20:03

Tomas Puverle wrote:
> John Bytheway wrote:
>
> > More subjectively, I prefer Rob's suggested endian_cast to swap.  I
> > don't associate this operation with swapping, and indeed in
> > some cases there is no swapping involved.
>
> I liked the earlier suggestion to rename "swap_in_place" to
> "swap" and the current "swap" to "swap_copy".

Actually, I used "swapped_copy" rather than "swap_copy" intentionally, but it isn't a big deal.

> Actually, now that I think about it, the cast<> notation may
> allow me to unify the swap/to/from functions into a single form:
>
> endian::cast<big_to_host>()  //explicit direction
> endian::cast<from_litle>()   //"to_host" is implicit
> endian::cast<to_big>()       //"from_host" is implicit

Where did "big_to_host" come from in your example?  Shouldn't that be "big_to_little?"  The "from_*" and "to_*" names lose value if you introduce "big_to_host" and friends.  "from_big" is little better than "big_to_host," for example.

The template arguments in your example assume the endian namespace, while the casts do not.  Real code would need to be like the following:

   endian::cast<endian::big_to_little>();
   endian::cast<endian::from_little>();
   endian::cast<endian::to_big>();

or this:

   using namespace boost::endian;
   cast<big_to_little>();
   cast<from_little>();
   cast<to_big>();

As you can see, "cast" is not so good in the latter; it is vague and harder to distinguish via textual search.  I named it "endian_cast" for those reasons and to make it more like the new-style casts.  How about putting "endian_cast" in the boost namespace and the other names in the boost::endian namespace, providing for the following usage?

   using namespace boost::endian;
   endian_cast<big_to_little>();
   endian_cast<from_little>();
   endian_cast<to_big>();

_____
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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