• Jarrett Billingsley (15/15) Oct 30 2007 This is driving me up the wall. I want to have a function like this:
• Don Clugston (6/29) Nov 01 2007 Do it in two levels.
• Jarrett Billingsley (6/11) Nov 01 2007 First thing I tried. This works for the explicit case, but you can't ca...
• Don Clugston (5/20) Nov 01 2007 Oh, yeah. Now I remember. You still have to put in a !(). Bummer.

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

This is driving me up the wall.  I want to have a function like this:

R func(R = int, T)(T t)
{

}

Where R can be specified but defaults to int, and T can be any type inferred 
from the parameter.  Of course this function signature doesn't work, and 
neither does anything else I've tried.  I want to be able to do:

    func(5); // R is int, T is typeof(5)
    func!(float)(5); // R is float, T is typeof(5)

The problem is that explicit instantiation disables IFTI making it 
impossible to derive T, and if I have multiple templates named 'func' and 
some of them are function templates and some aren't, it won't work with 
IFTI.

It seems that I can get one or the other, but not both.  Is there a 
solution? 

Don Clugston <dac nospam.com.au> writes:

Jarrett Billingsley wrote:
 This is driving me up the wall.  I want to have a function like this:
 
 R func(R = int, T)(T t)
 {
 
 }
 
 Where R can be specified but defaults to int, and T can be any type inferred 
 from the parameter.  Of course this function signature doesn't work, and 
 neither does anything else I've tried.  I want to be able to do:
 
     func(5); // R is int, T is typeof(5)
     func!(float)(5); // R is float, T is typeof(5)
 
 The problem is that explicit instantiation disables IFTI making it 
 impossible to derive T, and if I have multiple templates named 'func' and 
 some of them are function templates and some aren't, it won't work with 
 IFTI.
 
 It seems that I can get one or the other, but not both.  Is there a 
 solution? 
 
 

Do it in two levels.

template func(R=int)
{
    R func(T)(T t) {...}
}

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"Don Clugston" <dac nospam.com.au> wrote in message 
news:fgc15n$226b$1 digitalmars.com...
 Do it in two levels.

 template func(R=int)
 {
    R func(T)(T t) {...}
 }

First thing I tried.  This works for the explicit case, but you can't call 
it with IFTI, since func is no longer a function template.  I wish the 'is 
this a function template?' check were a little more lenient/intelligent in 
some cases. 

Don Clugston <dac nospam.com.au> writes:

Jarrett Billingsley wrote:
 "Don Clugston" <dac nospam.com.au> wrote in message 
 news:fgc15n$226b$1 digitalmars.com...
 Do it in two levels.

 template func(R=int)
 {
    R func(T)(T t) {...}
 }

 
 First thing I tried.  This works for the explicit case, but you can't call 
 it with IFTI, since func is no longer a function template.  I wish the 'is 
 this a function template?' check were a little more lenient/intelligent in 
 some cases. 
 
 

Oh, yeah. Now I remember. You still have to put in a !(). Bummer.
func!(long)(3.0i);
func!()(4.0);

That was the best I could find, around DMD 1.0.