Re: [boost] Breaking existing libraries

Subject: Re: [boost] Breaking existing libraries
From: Thorsten Ottosen (thorsten.ottosen_at_[hidden])
Date: 2008-11-23 07:21:23

Dave Handley skrev:
> Comments inlined:
> 
> Markus Werle writes:
> 
> <snip>

> I've got one final point to make here.  I went through and reviewed the 
> code changes in boost.range that Tom is referring to.  I wouldn't be 
> happy putting this type of code change through in my own libraries.  
> Changing the functionality of a default constructed object just to get 
> rid of a single test against bool in a couple of functions (ostensibly 
> for performance) seems to me misguided. 

That is of course a valid view. But take to the extreame, it means we 
would have to give up the "you don't pay for what you don't use" mantra.

> Furthermore, having different 
> functionality in debug and release, for most major users of a library, 
> is just dangerous.  The size and empty functions for example assert in 
> debug, but just silent fail in release.

"Silently fail" is a bit strong here. I mean, if there are any unit-test 
set up, I would expect them to trigger an assert in debug-mode. I don't 
consider that "silent".

>  The issingular function is even 
> worse, it tells you whether a range is singular in debug, but always 
> returns false in release.

IIRC, is_singular is not documented. So using it is on your own risk. It 
could disappear in the next release or whatever.

-Thorsten