• BCS (19/19) Nov 21 2005 How can you get the specialization parameters for a template from outsid...
• Sean Kelly (4/6) Nov 21 2005 You can't. This is why C++ defines a set of standard typedefs that must...
• BCS (10/16) Nov 21 2005 What, if any, problem arise with a syntax allowing that. Just as a start...
• Sean Kelly (8/24) Nov 21 2005 I'm not sure I like it, as it introduces symbols into the interface that...
• BCS (10/34) Nov 21 2005 ok, then how about public/package/private or somthing like that.
• Thomas Kuehne (23/64) Nov 25 2005 -----BEGIN PGP SIGNED MESSAGE-----
• BCS (21/52) Nov 26 2005 No good. What I'm looking for must work on an alias for a template membe...

BCS <BCS_member pathlink.com> writes:

How can you get the specialization parameters for a template from outside the
template? This is what I have tried.

template test(int i)
{
struct j {int k;};
}

int main()
{
alias test!(1).j t;		
alias test!(2).j u;

printf("%d\n", t.i);
printf("%d\n", u.i);
return 0;
}

The point of what I am trying is to do things like this:

alias test!(t.i + u.i) v;

If what I am trying to do is not possible or is rather convoluted, I would like
to propose that a simple way be provided to do this. Such as allow access to
them as properties.

Sean Kelly <sean f4.ca> writes:

BCS wrote:
 How can you get the specialization parameters for a template from outside the
 template? This is what I have tried.

You can't.  This is why C++ defines a set of standard typedefs that must 
be implemented by containers and such.


Sean

BCS <BCS_member pathlink.com> writes:

In article <dltjb9$l0q$1 digitaldaemon.com>, Sean Kelly says...
BCS wrote:
 How can you get the specialization parameters for a template from outside the
 template? This is what I have tried.

You can't.  This is why C++ defines a set of standard typedefs that must 
be implemented by containers and such.


Sean

What, if any, problem arise with a syntax allowing that. Just as a starting
point, how about this:

template t(int i, T)
{
T fn(){...}
}

int t_i = t!(0,int).i;   // sets t_i to 0;
t!(0,int).T      t_T;    // t_T is of type int
t!(1,real).fn.T  t_fn_T; // t_fn_T is of type real

Sean Kelly <sean f4.ca> writes:

BCS wrote:
 In article <dltjb9$l0q$1 digitaldaemon.com>, Sean Kelly says...
 BCS wrote:
 How can you get the specialization parameters for a template from outside the
 template? This is what I have tried.

 You can't.  This is why C++ defines a set of standard typedefs that must 
 be implemented by containers and such.

 
 What, if any, problem arise with a syntax allowing that. Just as a starting
 point, how about this:
 
 template t(int i, T)
 {
 T fn(){...}
 }
 
 int t_i = t!(0,int).i;   // sets t_i to 0;

I'm not sure I like it, as it introduces symbols into the interface that 
might be implementation details.  I'd rather stick to the manual method:

class C(int i) {
     const int count = i;
}

const int c = C!(1).count;



Sean

BCS <BCS_member pathlink.com> writes:

In article <dltlpm$n12$1 digitaldaemon.com>, Sean Kelly says...
BCS wrote:
 In article <dltjb9$l0q$1 digitaldaemon.com>, Sean Kelly says...
 BCS wrote:
 How can you get the specialization parameters for a template from outside the
 template? This is what I have tried.

 You can't.  This is why C++ defines a set of standard typedefs that must 
 be implemented by containers and such.

 
 What, if any, problem arise with a syntax allowing that. Just as a starting
 point, how about this:
 
 template t(int i, T)
 {
 T fn(){...}
 }
 
 int t_i = t!(0,int).i;   // sets t_i to 0;

I'm not sure I like it, as it introduces symbols into the interface that 
might be implementation details.  I'd rather stick to the manual method:

class C(int i) {
     const int count = i;
}

const int c = C!(1).count;



Sean

ok, then how about public/package/private or somthing like that.
Further more how can the above be extended to somthing like:

template fn(int I)
{
void fn(){...}
const int count = I
}

alias fn!(1).fn() hidden;

hidden.count // error: can't get that from this

Thomas Kuehne <thomas-dloop kuehne.cn> writes:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

BCS schrieb am 2005-11-22:
 In article <dltlpm$n12$1 digitaldaemon.com>, Sean Kelly says...
BCS wrote:
 In article <dltjb9$l0q$1 digitaldaemon.com>, Sean Kelly says...
 BCS wrote:
 How can you get the specialization parameters for a template from outside the
 template? This is what I have tried.

 You can't.  This is why C++ defines a set of standard typedefs that must 
 be implemented by containers and such.

 
 What, if any, problem arise with a syntax allowing that. Just as a starting
 point, how about this:
 
 template t(int i, T)
 {
 T fn(){...}
 }
 
 int t_i = t!(0,int).i;   // sets t_i to 0;

I'm not sure I like it, as it introduces symbols into the interface that 
might be implementation details.  I'd rather stick to the manual method:

class C(int i) {
     const int count = i;
}

const int c = C!(1).count;



Sean

 ok, then how about public/package/private or somthing like that.
 Further more how can the above be extended to somthing like:

 template fn(int I)
 {
 void fn(){...}
 const int count = I
 }

 alias fn!(1).fn() hidden;

 hidden.count // error: can't get that from this


| import std.stdio;
|
| template fn(int I)
| {
|     void fn(){...}
|     const int count = I
| }
| alias fn!(1) hidden;
|
| int main()
| {
|     writefln("%s", hidden.count);
|     return 0;
| }

Thomas


-----BEGIN PGP SIGNATURE-----

iD8DBQFDh8W+3w+/yD4P9tIRAixpAKC2SxssMjy2BuwShZ+fJtVApr98cgCfQ+C+
TM7c2K2EAzE/usuqq/zOzJc=
=NjvR
-----END PGP SIGNATURE-----

BCS <BCS_member pathlink.com> writes:

No good. What I'm looking for must work on an alias for a template member. e.g.

alias fn!(1).fn() hidden;
hidden()     // this must be a function
hidden.count // this must be a const int

The real purpose of this would be something like this

template t(int i)
{
typedef real t;
}


template math(T, U)
{
// abusing the syntax to say:
// T & U must be from template t but I don't care what i is.
static assert(is(T == t!(*).t) && is(U == t!(*).t);

t!(T.i + U.i).t opMul(T a, U b) { return a*b; }
t!(T.i - U.i).t opDiv(T a, U b) { return a/b; }

t!(T.i).t opAdd(T a, T b) { return a+b; }
t!(T.i).t opSub(T a, T b) { return a-b; }
}

In article <u6tk53-rdd.ln1 birke.kuehne.cn>, Thomas Kuehne says...
BCS schrieb am 2005-11-22:
 In article <dltlpm$n12$1 digitaldaemon.com>, Sean Kelly says...



.....
 ok, then how about public/package/private or somthing like that.
 Further more how can the above be extended to somthing like:

 template fn(int I)
 {
 void fn(){...}
 const int count = I
 }

 alias fn!(1).fn() hidden;

 hidden.count // error: can't get that from this


| import std.stdio;
|
| template fn(int I)
| {
|     void fn(){...}
|     const int count = I
| }
| alias fn!(1) hidden;
|
| int main()
| {
|     writefln("%s", hidden.count);
|     return 0;
| }

Thomas