Regex named-group and backreference syntax

[Xueming Shen]

RFE#6878475 has been filed to trace this issue.

At this point we are going to update the doc and implementation to
(1)disallow the group name started with digit character
(2)use ${name} for the group reference in replacement string.

The \k<n> and ${n} can leave for further discussion (whether or not we 
really
need this NEW feature, while there is existing syntax that can do the 
job just fine).

Sherman

Mark Reinhold wrote:
>> Date: Wed, 02 Sep 2009 18:55:49 +0100
>> From: Andrew John Hughes <gnu_andrew at member.fsf.org>
>>     
>
>   
>> 2009/9/2 Mark Reinhold <mr at sun.com>:
>>     
>>> I'd say ${name} is the best option here given that it will be familiar,
>>> at least, to Perl and .NET developers.
>>>       
>> It's also used for substitution in shell and Makefiles :)
>>     
>
> That too!
>
> - Mark
>