[boost] Re: Math constants - updated.

From: Tobias Schwinger (tschwinger_at_[hidden])
Date: 2005-05-09 05:22:34

Andy Little wrote:
> 
> "Tobias Schwinger" <tschwinger_at_[hidden]> wrote
> 
>> Andy Little wrote:
>>
>>>
>>> "Tobias Schwinger" <tschwinger_at_[hidden]> wrote
> 
> 
>>>> - there is no way to pass constants as a type template argument.
>>>
>>>
>>> ( IOW  use a function ..? )
>>
>>
>> No. A class somehow like this:
>>
>> template<typename T> struct name;
>>
>> template<> struct name<TYPE>
>> {
>> operator TYPE() const { return ... };
>> TYPE operator() () const { return ... };
>> };
> 
> 
> FWIW I had alook at this approach yesterday. see "test.cpp" attached. I 
> think it
> could be made to work. In unary contexts it requires explicit 
> conversion, but I
> guess there is no way around that.  Of course you need an object..
> boost::math::pi pi ; or a temporary.. boost::math::pi() ;. However I 
> guess this
> means you can use either pi or pi() syntax ... :-)

Is it asked too much to let the user just specify the type ?

Every variable declaration requires a type so why make things more complicated 
for constants ?

C++ is a strictly typed language and I really can't see the point in emulating 
loose typedness for constants (especially since you can "declare" a pi constant 
by instantiating an object, e.g: "pi<float> PIf;").

Regards,

Tobias