'!' and naming conventions

[Brad Anderson via Digitalmars-d-learn]

On Wednesday, 18 June 2014 at 20:55:36 UTC, cym13 wrote:
> Hello,
>
> I see a lot of functions and other stuff with a '!' in the name
> such as 'bitfields!' or 'ctRegex!'. What does it mean exactly? 
> In
> scheme, we use such a convention to warn that a function is not
> pure, but I don't see the point of using it that way in D as
> there are other way to express it.
>
> Moreover, I'm looking for a style guide of D, something like the
> PEP8 for python. Is there anything like that?
>
> Thanks!

The ! specifies that a template argument list follows.

auto fun(T)(T a, T b) { return a * b; }

void main()
{
     // fun can be called using several different ways:
     fun!(int)(1, 2); // Specifying the template arguments
     fun!int(1, 2);   // If there is only one template argument the
                      // parens can be omitted
     fun(1, 2);       // IFTI can be used to figure out the types 
for you
}

There is a style guide on the website: 
http://dlang.org/dstyle.html

Personally I just consider this a Phobos contributor style guide 
and not like a PEP8 style guideline.