Re: [boost] Endian library - request for comments

From: Yuval Ronen (ronen_yuval_at_[hidden])
Date: 2006-05-31 18:26:40

Beman Dawes wrote:
> Back in 1999 and 2000, there was discussion of a Boost Endian library to 
> provided portable big and little endian integer types. I've dusted off 
> some old code from Darin Adler, gotten his permission to use the new 
> Boost license, and have put together a library.
> 
> A zip file of the whole library is available at 
> http://mysite.verizon.net/~beman/endian.zip

I think an Endian library would be most useful in Boost.
However, I have some doubts about this proposal. It seems to me that it 
tries to solve two problems at once, and it doesn't look good. The first 
issue is providing integer types of various sizes/alignments. the second 
issue is Endianness. Wouldn't it be better to separate those two?

If we want to provide with integer types of various sizes/alignments, 
then why shouldn't they allowed to be with native Endianness? And the 
complimentary question - if we want to provide with specific Endianness 
types, then why can't we do it with regular types such as int or long?

What I'm suggesting is to provide a library for integer types of various 
sizes/alignments. This already partly exists in Boost.Integer (AFAIK, 
support for alignment is missing there). So Boost.Integer needs to be 
expanded for this.

Then, there's also a need for Endian classes which are templated with 
some integer type. Something like:

     boost::big_endian<int> x;
     boost::little_endian<boost::uint32_t> y;
     boost::big_endian<boost::signed_7_bytes_aligned> z;

This way, the full scope of possibilities is provided.

> The docs can be read at http://mysite.verizon.net/~beman/endian.html

Just a tiny thing: a sentence describing how to convert to/from native 
integers would be very helpful. I know I could find it in the code, if 
I'd bother to look, and the code sample also implies there's an implicit 
conversion from native types, but what about the other way, and anyway, 
I think a short explaining sentence is a good idea.

Yuval