Re: Suggestion to change a config.hpp macro

From: Daryle Walker (darylew_at_[hidden])
Date: 2001-03-12 16:25:11

on 3/11/01 8:40 PM, David Abrahams at abrahams_at_[hidden] wrote:

> ----- Original Message -----
> From: "Daryle Walker" <darylew_at_[hidden]>
> 
>> The BOOST_STATIC_CONSTANT macro was added to <boost/config.hpp> two days
>> ago.  I think it has a slight inefficiency.  Here's a copy:
[SNIP]

>> My question is: why do we make the user explicitly add the "="?  What's
>> wrong with (excuse any line-wrap my e-mail client adds):
[SNIP]

> It's a choice between ',' and '='.
> In this case, '=' is more memnonic than ','
> The use of the macro resembles the "ideal" declaration:
> 
> static const         bool is_fake = !is_real  ;
> BOOST_STATIC_CONSTANT(bool, is_fake = !is_real);

>> Is there some subtle point of macro definitions that keeps this from working,
> 
> No
> 
>> or did we make a silly oversight?  If it was an oversight
> 
> Where's the oversight? The silliness? Where's the LOVE?!
> 
> Okay, I'm getting carried away, but seriously: what's wrong with it the way
> it is?

It supports a convention that the user has to remember to use.  If the user
forgets the '=', bad stuff may happen.  The ',' isn't a convention, it would
be a mandatory separator between macro arguments.  If the alternative method
is screwed up, then the preprocessor would complain about a misused macro.
If the current method is screwed up, then the preprocessor will carry it
anyway and the user will get a strange regular-compile-time error.

>> can we change the macro to this form?
> 
> Not without good cause.
> 
>> Yes, I know that I'm asking for an incompatible change, but the macro is only
>> a few days old, so I don't think that there's too much code to change.
>> Within Boost 1.21.0 itself, the macro (name) appears 207 times in 12 files.
>> It could be updated in approximately a day, probably by a team of people with
>> CVS write access.  (I'll change them if you guys insist, but I would have to
>> send Beman a ZIP file to merge into CVS.)
> 
> That's a lot of work for a change which buys little or nothing (even less
> than nothing if you consider the memnonic value of '=').

It not too much work; I've already done it so we don't have to worry about
that step (if it's approved).  I'm not sure the mnemonic value is worth the
loss of (a little) safety.

-- 
Daryle Walker
Mac, Internet, and Video Game Junkie
darylew AT mac DOT com