[cmake-developers] slow regex implementation in RegularExpression

[Bill Hoffman]

On 11/22/2011 4:39 PM, Brad King wrote:

> It is tempting to always require explicit requests for new TRE behavior,
> such as using "TRE" instead of "REGEX" in keyword locations, but one
> advantage of using a policy is that over time the old behavior will
> disappear completely from usage.
>
I am pretty sure the last time we talked about adding a new regex we 
talked about requiring explicit requests.  I think this would be a much 
safer approach.  I am really scared that this regex will not be 
compatible with the old one, and it will break lots of stuff in very 
subtle ways that are hard for people to detect.  It is not that much 
code to have both.  Where performance is an issue, we can swap it out, 
and when people need better regex they can use TRE as well.  I don't 
think the pain will be worth getting rid of the old usage.

-Bill