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digitalmars.D.learn - Operator overloading

reply silverling <este_aqui_ hot_mail.com.remove.underscores> writes:
I have overloaded the multiplication operator like this

opMul(T)(T number){...}
opMulAssign(T)(Tn number){...}

Now, I want another multiplier to multiply with a specific class (itself) so
generally, one would write (after the other overloads)

opMult(T:classA)(T multiplier)

as it is specified on the language specs
http://www.digitalmars.com/d/template.html under the "Specialization" section.
However, DMD refuses to compile, saying that "specialization not allowed for
deduced parameter T". I'd really hate to have to overload the opMul with
real/long/cfloat/classA/etc. How can I fix this?
May 10 2007
parent reply "Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:
"silverling" <este_aqui_ hot_mail.com.remove.underscores> wrote in message 
news:f1vqkm$11li$1 digitalmars.com...

I have overloaded the multiplication operator like this

 opMul(T)(T number){...}
 opMulAssign(T)(Tn number){...}

 Now, I want another multiplier to multiply with a specific class (itself) 
 so generally, one would write (after the other overloads)

 opMult(T:classA)(T multiplier)

 as it is specified on the language specs 
 http://www.digitalmars.com/d/template.html under the "Specialization" 
 section. However, DMD refuses to compile, saying that "specialization not 
 allowed for deduced parameter T". I'd really hate to have to overload the 
 opMul with real/long/cfloat/classA/etc. How can I fix this?


Use static if and is() inside the function:

blah opMul(T)(T number)
{
    static if(is(T : classA))
    {
        // code for classA version
    }
    else
    {
        // for other types
    }
}
May 10 2007
parent reply BCS <BCS pathlink.com> writes:
Jarrett Billingsley wrote:

 "silverling" <este_aqui_ hot_mail.com.remove.underscores> wrote in message 
 news:f1vqkm$11li$1 digitalmars.com...
 

I have overloaded the multiplication operator like this

opMul(T)(T number){...}
opMulAssign(T)(Tn number){...}

Now, I want another multiplier to multiply with a specific class (itself) 
so generally, one would write (after the other overloads)

opMult(T:classA)(T multiplier)

as it is specified on the language specs 
http://www.digitalmars.com/d/template.html under the "Specialization" 
section. However, DMD refuses to compile, saying that "specialization not 
allowed for deduced parameter T". I'd really hate to have to overload the 
opMul with real/long/cfloat/classA/etc. How can I fix this?


 
 
 Use static if and is() inside the function:
 
 blah opMul(T)(T number)
 {
     static if(is(T : classA))
     {
         // code for classA version
     }
     else
     {
         // for other types
     }
 } 
 
 


I really wish there was a static switch

static switch(T)
{
	case classA:
	{
	}

	case int:
	{
	}

	default:
	{
	}
}

fall thought wouldn't work for it though so it would be kind of odd.
May 10 2007
parent Chris Nicholson-Sauls <ibisbasenji gmail.com> writes:
BCS wrote:

 Jarrett Billingsley wrote:

 "silverling" <este_aqui_ hot_mail.com.remove.underscores> wrote in 
 message news:f1vqkm$11li$1 digitalmars.com...


 I have overloaded the multiplication operator like this

 opMul(T)(T number){...}
 opMulAssign(T)(Tn number){...}

 Now, I want another multiplier to multiply with a specific class 
 (itself) so generally, one would write (after the other overloads)

 opMult(T:classA)(T multiplier)

 as it is specified on the language specs 
 http://www.digitalmars.com/d/template.html under the "Specialization" 
 section. However, DMD refuses to compile, saying that "specialization 
 not allowed for deduced parameter T". I'd really hate to have to 
 overload the opMul with real/long/cfloat/classA/etc. How can I fix this?



 Use static if and is() inside the function:

 blah opMul(T)(T number)
 {
     static if(is(T : classA))
     {
         // code for classA version
     }
     else
     {
         // for other types
     }
 }


 
 I really wish there was a static switch
 
 static switch(T)
 {
     case classA:
     {
     }
 
     case int:
     {
     }
 
     default:
     {
     }
 }
 
 fall thought wouldn't work for it though so it would be kind of odd.


I'd welcome it, regardless.

-- Chris Nicholson-Sauls
May 10 2007