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digitalmars.D.learn - simple struct template

reply Hendrik Renken <funsheep gmx.net> writes:
Hi,

i've wrote a simple struct template:

struct Vector(T)
{
    T x;
    T y;
    T z;
}

now i would like to define some aliases to make my programming life easier:

Vectorf for Vector!(float)
Vectord for Vector!(double)

void main(char[][] args)
{
    Vectorf v;
    v.x = 0.2f;
}


is that possible? i tried

mixin Vector!(float) Vectorf;
alias Vector!(float) Vectorf;

with gdc 0.23. both dont work.

regards
Hendrik
Mar 30 2007
parent reply Daniel Keep <daniel.keep.lists gmail.com> writes:
Hendrik Renken wrote:

 Hi,
 
 i've wrote a simple struct template:
 
 struct Vector(T)
 {
    T x;
    T y;
    T z;
 }
 
 now i would like to define some aliases to make my programming life easier:
 
 Vectorf for Vector!(float)
 Vectord for Vector!(double)
 
 void main(char[][] args)
 {
    Vectorf v;
    v.x = 0.2f;
 }
 
 
 is that possible? i tried
 
 mixin Vector!(float) Vectorf;
 alias Vector!(float) Vectorf;
 
 with gdc 0.23. both dont work.
 
 regards
 Hendrik



alias Vector!(float) Vectorf;
alias Vector!(double) Vectord;

Should work; if not, what error message is the compiler giving you?

	-- Daniel

-- 
int getRandomNumber()
{
    return 4; // chosen by fair dice roll.
              // guaranteed to be random.
}

http://xkcd.com/

v2sw5+8Yhw5ln4+5pr6OFPma8u6+7Lw4Tm6+7l6+7D
i28a2Xs3MSr2e4/6+7t4TNSMb6HTOp5en5g6RAHCP  http://hackerkey.com/
Mar 30 2007
parent reply Hendrik Renken <funsheep gmx.net> writes:
 alias Vector!(float) Vectorf;
 alias Vector!(double) Vectord;
 
 Should work; if not, what error message is the compiler giving you?
 
 	-- Daniel
 



dmd on linux32, gdc 0.23 on mac os:
"template instance forward reference to template declaration Vector(T)"

hendrik
Mar 30 2007
parent reply =?ISO-8859-1?Q?Jari-Matti_M=E4kel=E4?= <jmjmak utu.fi.invalid> writes:
Hendrik Renken wrote:

 alias Vector!(float) Vectorf;
 alias Vector!(double) Vectord;

 Should work; if not, what error message is the compiler giving you?



 "template instance forward reference to template declaration Vector(T)"



Put your aliases after the struct definition:

struct Vector(T)
{
   T x;
   T y;
   T z;
}

alias Vector!(float) Vectorf;

void main(char[][] args)
{
   Vectorf v;
   v.x = 0.2f;
}
Mar 30 2007
parent reply Hendrik Renken <funsheep gmx.net> writes:
 Put your aliases after the struct definition:
 
 struct Vector(T)
 {
    T x;
    T y;
    T z;
 }
 
 alias Vector!(float) Vectorf;
 
 void main(char[][] args)
 {
    Vectorf v;
    v.x = 0.2f;
 }



ah, thanks for your help, now i understand the error message ^^.

Need to bother you once again.

how do i overload opCall, when i want to return the appropriate type, i 
tried the obvious (at least for me):


struct Vector(T)
{

     public: T x, y, z;
	
     static Vector!(T) opCall(T x, T y, T z)
     {
	this.x, y, z = (x, y, z);
     }
	
}


but then the compiler complains:

function Vector.Vector!(float).Vector.opCall expected to return a value 
of type Vector!(float)

where i have defined the aliases.


regards,
hendrik
Mar 30 2007
parent reply Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:
Hendrik Renken wrote:

 how do i overload opCall, when i want to return the appropriate type, i 
 tried the obvious (at least for me):
 
 
 struct Vector(T)
 {
 
     public: T x, y, z;
     
     static Vector!(T) opCall(T x, T y, T z)
     {
     this.x, y, z = (x, y, z);



change that to:
	Vector!(T) result;
	result.x = x;
	result.y = y;
	result.z = z;
	return result;

Static member function don't _have_ a "this"


     }
     
 }
 
 
 but then the compiler complains:
 
 function Vector.Vector!(float).Vector.opCall expected to return a value 
 of type Vector!(float)



Because you didn't actually return anything.
Mar 30 2007
next sibling parent Hendrik Renken <funsheep gmx.net> writes:
Frits van Bommel wrote:

 Hendrik Renken wrote:

 how do i overload opCall, when i want to return the appropriate type, 
 i tried the obvious (at least for me):


 struct Vector(T)
 {

     public: T x, y, z;
         static Vector!(T) opCall(T x, T y, T z)
     {
     this.x, y, z = (x, y, z);



 change that to:
     Vector!(T) result;
     result.x = x;
     result.y = y;
     result.z = z;
     return result;
 
 Static member function don't _have_ a "this"
 
 Because you didn't actually return anything.



*banging the head against the table*

seems, as if my brain takes a long nap. sorry for bothering.
Mar 30 2007
prev sibling parent =?UTF-8?B?SmFyaS1NYXR0aSBNw6RrZWzDpA==?= <jmjmak utu.fi.invalid> writes:
Frits van Bommel wrote:

 Hendrik Renken wrote:

 how do i overload opCall, when i want to return the appropriate type,
 i tried the obvious (at least for me):


 struct Vector(T)
 {

     public: T x, y, z;
         static Vector!(T) opCall(T x, T y, T z)
     {
     this.x, y, z = (x, y, z);



 change that to:
     Vector!(T) result;
     result.x = x;
     result.y = y;
     result.z = z;
     return result;



Also I think you can use just Vector instead if Vector!(T) in those
routines. At least it works that way. Those extra letters are sooo
expensive.
Mar 30 2007