Re: [boost] Attn metaprogrammers! [Better Enums] More complete release - feedback requested

Subject: Re: [boost] Attn metaprogrammers! [Better Enums] More complete release - feedback requested
From: Anton Bachin (antonbachin_at_[hidden])
Date: 2015-06-08 22:53:57

> On Jun 8, 2015, at 21:27, Gavin Lambert <gavinl_at_[hidden]> wrote:
> 
> On 9/06/2015 13:16, Anton Bachin wrote:
>>> (As an aside, it was quite a handy data structure.  It was mainly intended
>>> for string-to-enum conversions but because of the way it was templated it
>>> could be abused to do string-to-member-pointer conversions as well, which
>>> enabled all sorts of interesting reflection scenarios.)
>> 
>> I am curious to know what this was, it sounds interesting.
> 
> It wasn't really all that interesting.  It was just a "data table class" with some helper macros that let you define a static const structure private to a .cpp file (and initialised at compile time) to contain the string and value, plus a "lookup class" that was declared in the .h (as a static global) that was initialised with the address of the table. All the actual searching was done at runtime by the lookup class, with the table class basically just POD. <snip>

That’s useful to know, thank you. I’d like to make Better Enums the join (meet?)
of good approaches, so your message was helpful both for the method and for the
use cases.

I’ve been thinking about the serialization scenario, in particular. I don’t know
the full range of what you needed, but would something like the ability to alias
constants to each other, and iterate over unique values only, have been
sufficient? For example, a declaration like

…OldName, MoreNames, NewName = OldName, …

where OldName is for compatibility, and NewName is what you intend to use in
your code. Converting the string "OldName" results in the same numeric value as
NewName.

When iterated over as values, the value of OldName/NewName would get visited
only once. Also, when converting to string, there could be some convention such
as the first name declared is the preferred one (actually the opposite of what I
wrote above).