Review of std.net.isemail part 2

[Robert Jacques]

On Sun, 03 Apr 2011 09:49:44 -0400, Andrei Alexandrescu  
<SeeWebsiteForEmail at erdani.org> wrote:

> On 4/3/11 6:38 AM, Jacob Carlborg wrote:
>> On 2011-04-02 23:33, Jonathan M Davis wrote:
>>> On 2011-04-02 09:26, Jacob Carlborg wrote:
>>>> On 2011-04-01 11:01, Jonathan M Davis wrote:
>>>>> On 2011-03-29 14:06, Jacob Carlborg wrote:
>>>>>> I've made a few minor changes:
>>>>>>
>>>>>> * Renamed EmailStatusCode.Off -> None and On -> Any
>>>>>> * Added and clarified the documentation for EmailStatusCode.Any and
>>>>>> None
>>>>>> * Updated the documentation
>>>>>>
>>>>>> Github: https://github.com/jacob-carlborg/phobos/tree/isemail
>>>>>> Docs: http://dl.dropbox.com/u/18386187/isemail.html
>>>>>
>>>>> Shouldn't isEmail have a template constraint which verifies that the
>>>>> e-mail variable is a valid string type? Also, it would probably be
>>>>> better to use Char instead of T for the type. It's clearer that way.  
>>>>> I
>>>>> believe that that's what std.string does.
>>>>
>>>> That's a good idea.
>>>
>>> I'd say that pretty much every template should have a template
>>> constraint on
>>> it. I'm not sure that I've ever seen a template which was flexible
>>> enough that
>>> it would compile with anything you gave it, and if there's an argument
>>> that
>>> you can give it which won't compile with it, it should fail the  
>>> template
>>> constraints, otherwise the error messags are much harder to understand
>>> and
>>> track down.
>>
>> I've added a static assert with a custom error message. I think static
>> asserts can give better error messages than template constraints.
>
> Please use a template constraint. This is the right thing to do and we  
> use it throughout Phobos.
>
> Thanks,
>
> Andrei

Also, static assert doesn't compose with is(typeof(...)) and  
__traits(compiles,...). (It stops the compiler if it's every evaluated)  
I'd recommend simply putting a string on an empty line over static assert:

static assert(...,"My error message");

static if(...) "My error message";