Template constraints in D

[Bill Baxter]

Sean Kelly wrote:
> == Quote from Bill Baxter (dnewsgroup at billbaxter.com)'s article
>> Sean Kelly wrote:
>>> == Quote from bearophile (bearophileHUGS at lycos.com)'s article
>>>> Walter Bright:
>>>>> http://www.digitalmars.com/d/2.0/concepts.html
>>>> They look nice (but I may use a bigger list of examples to understand how
> they can be used). What
>>> can they do that can't be done with the things already present?
>>>
>>> Nothing.  But it's a very convenient syntactic sugar on top of existing
>>> techniques, such as:
>>>
>>>
> http://www.digitalmars.com/d/archives/digitalmars/D/Stroustrup_s_talk_on_C_0x_57104.html#N5737
>>> 9
>>>
>>> Walter had even asked me to write an article about this, but I never
>>> followed through :p
>>>
>>> I will say that the __traits(compiles, blah) trick is totally awesome.  I
>>> was trying to do this in D 1.0 the other day and couldn't find a way to
>>> make it work.  Figures it would require D 2.0.  *sigh*
>> DeeGirl's trick works in D 1.x doesn't it?
>> I.e. a template function + is(typeof(thatTemplateFunction!(T)))
> 
> Not as far as I know.  This is the first thing I tried, and it gave me a compile
> error when the function couldn't be instantiated.

Ok, so I guess the contents of thatTemplateFunction!(T) have to go 
in-line.  Which makes it a bit more of a pain.  But I think you can 
still achieve the same effect.

--bb